I'm studying Fine Art (BA, hons, 2nd year student) at the Chelsea College of Arts campus at the UAL and although I'm obviously doing a different course gtom the one being asked about here, I would like to back you up that this is my experience at the UAL here so far too.
At the UAL, you get given a lot of freedom- A HELL OF A LOT OF FREEDOM. Now, this might sound like a dream come true for some people who feel like they've always felt stifled in their more traditional "on rails" college/school creative courses (where everything feels like jumping through a series of hoops all the time), but its a massive adjustment to get used to when you've always been used to being in a classroom where's there's often (or always) a teacher present, where you're given challenges and themes to work with and where everyday, there's some semblence of a schedule and structure to what your doing and the pacing of everything.
Pros: The tutors and technicians at the UAL are all TOP CLASS- many are very successful professionals in their chosen fields in they're own right (some are even semi-famous or famous!), many are genius's and all are extremely knowledgeable and talented. Furthermore, the libraries at the UAL are superb, the workshop classes are diverse and plentiful, and there are always a lot of opportunities both in and outside of the university being advertised. And if this were not enough, industry contacts (such as gallery and other business owners) regularly attend UAL student events and on my course (Fine Art), successful professional artists are regularly invited in to give talks.
Cons: Contact with tutors is often limited and aside from a general year meeting or lecture once a week, you are given almost no schedule or framework to work within at all (and even when it comes to the year meetings and lectures, no-one is going to scold or chase you if you don't turn up to those!). Once in a while (like maybe once everything 2-4 weeks) you might get a half hour 1-2-1 session with your tutor (who will mostly just ask you how you're doing and give you some advice, such as stuff helpful to your research or useful questions you should be asking) but beyond that, there's not a lot of guaranteed contact with everyone.
Overall: So you have to apply yourself- if you want to get your money's worth for your course, then you need to come up with your own schedule, appy for those workshops, go to those lectures, read your emails regularly and take up opportunities both in and outside of the course. If you fail to do this, nobody is going to scoop you back up but equally, if freedom (especially creative freedom) is what you desire in a course (and you're the kind to take your own initiative, take responsibility for your motivation and have a good attitude towards seeking help when you need it), then I would say that this university is very suited to you.
My experience so far: I thought that what I craved before coming here was total creative freedom, and I don't think that I was incorrect in this (I definitely do flourish more in an environment of freedom, and freedom is still what I value & seek). But it can't be underestimated how large the leap up is here from doing a regular college or school course to doing a UAL course, even you've so far been a pretty independent student (basically even if freedom is your game, near-total freedom still takes some adjusting to).
Whilst I managed to learn how to swim and not sink and generally get my **** together here (which was very challenging at times; despite being a top student at my former college, both beginnings of my 1st and 2nd years at the UAL began with me experiencing big bouts of depression relating from some long standing mental health issues of mine, which then led to problems finding my footing, developing a sense of direction and applying myself acdemically at the start), I'm also consciously aware that some people have fallen through the cracks and gotten lost the expansive freedom here, and that people like this span all 3 years of the standard BA hons Degree courses available.
1st year woes: The most common reason that I've observed for 1st years to seriously struggle, appears to centre on problems adjusting to massive mark-up in freedom and lack of structure here, which can easily lead to isolation and declining levels of attendence if don't take a proactive and self-aware attitude. These problems can in turn generate a whole number of issues spanning from anxiety, depression and agoraphobia, to self-esteem, confidence and an overall loss of sense of life direction (you come to university with all these ideas and then before you know it, everything you once knew is gone and now you're struggling to do anything). The 1st year is also many people's 1st experience living away from their families and aside from home sickness, it can be very easy to get worn down by disputes and experiences with roommates; unless you're very fortunate, you'll guaranteed be sharing a place with a number of other people and not only does that take some adjusting to, but that even despite your bestest efforts, you might still find living with other people very challenging. For example, you might struggle living with people who have serious mental health issues, who are exceptionally unhygienic & lazy, people who love drama or controlling others, who to party all night long (without a care to who they're keeping up with their late-night antics), people who barely speak your language or are very antisocial, or even all of the above (and more!). I know of almost no people who got through the 1st year without experiencing some struggles living with other people and the people I know who did drop out, mostly did because these kinds of issues (the intense freedom, the independence, and struggling with it all etc) that ultimately left them feeling like they were unprepared for university (and needed another year or so before they took on this chapter in their life). I was also aware of one person who dropped out of uni altogether because it was only upon starting it that they realized that what they really wanted to be be doing was an apprenticeship instead (but I guess that's uni for you- its not just about getting grades and experiences, but also figuring out what you really want to do).
2nd year woes: Whilst the 1st year is generally super easy to pass though (acedemically speaking), this can create a false sense of security in the 2nd year, where you experience a massive mark-up in not just the increasing amount of criteria that you're judged and held to account by, but also the things at which you're increasingly expected to achieve (for example, one challenge we were set was forming a collective with other people and putting on an entire exhibition in an off-site location which we not only had to find and create thoughtful artworks for, but even pay for and advertise by ourselves). Being lured into a false sense of security in the 1st year, a lot of people struggle to keep up with the 2nd year because they make the mistake of taking on a 2nd job to pay bills (its something you could probably juggle without too many problems in the 1st year, but in the 2nd year is exceptionally difficult to balance on top of the course). Others get hooked into a partying lifestyle and surround themselves with too much of a lackadaisical crowd; there are groups of people at uni who whilst they might be full of fun 'n popular peeps to hang around with, some will certainly discourage and drag you down in your work, especially if you try to develop any kind of real work ethic attitudes towards your work ("misery loves company", and those who don't want to take their course seriously tend to have a habit of discouraging others from doing so too). Other people also simply experience issues because they expect the 2nd year to be as cushty as the 1st (where they might have not developed their work ethic as much as they should have) and struggle to find their footing where it counts.
Note: Please note that I don't want to make it sound like everyone who struggles or drops out in the 1st or 2nd years does so because they've failed or fallen short in some sort of way, a lot of stuff can happen in life that's well beyond your control or abilities that can make even the best of us struggle or drop out. I do feel a little uncomfortable sharing my observations as I ultimately can't account for other people's life experiences and because I'm also aware that some people struggled through some terrible things that wasn't theirs or the universities doing nor fault.
3rd year woes: I'm not a 3rd year (yet! That starts in September), but I knew quite a few 3rd years in the year above me who've just graduated, and whilst some of them approached the end of their course fighting and full of confidence, quite a few seemed massively jaded with the whole course. Some of these jaded 3rd years were simply jaded with art courses in general, realizing how little difference art courses can make in the real world job market (whilst UAL courses are worth the paper they're written on, in general art courses are also not directly as translatable into employment as a lot of other subjects can be), whilst others were at a point of viewing what they got for their money as being little more than a glorified "free" studio (I say "free" in student debts sense of "free") that came with a bunch of workshops and some advice (I would ultimately disagree with this, though I can see where they are coming from).
I think its also a pretty standard thing to go through at least a couple of existential crisis's at university. And the art world (and doing art) is tough; not only does art require you to repeatedly dip into your reserves of creative energy (and applying oneself creatively in studio for hours on end is mentally and physically exhausting), but there is so much competition and so little guarantee in the world of art in general. Whilst I know one older guy who did his Masters in painting at the UAL (Chelsea College of Arts- he's now a PHD student studying performance at CSM) who told me that the course was worth the paper it was written on (he said that the UAL is very internationally recognised and highly regarded institution and that everywhere he went, employers recognised it on his CV), a lot of graduates still struggle to find employment and create a living from their creativity not because the UAL fails them, but simply because this was life is in the world of employable creativity: tough.
I can't say exactly how much people are prepared for life post-university in the 3rd year (because I haven't begun it yet), but my experiences so far are that the university is being honest with us about the challenges ahead and that it does display (and evidence) a helpful attitude towards helping graduated students (for example it helps students find jobs, even offering students employment opportunities at the uni itself). But it does also appear like the 3rd year is very much an extension of the 2nd year, with more of the mixture of being offered a lot of opportunities whilst being largely left to your own devices and being held to more criteria. I feel like the uni helps you to figure out and develop your practice (and potentially fly high) but that equally, if you fall through the net and struggle, you've already been placed into a position where you have no-one else but yourself to blame for that (in a place that offers so much to students, can anyone blame the university for anything if they don't do well...?).
Welbeing: In terms of mental health, there is a lot of support available for all that. And I do believe that the tutors genuinely care about students; I've witnessed (and 1st hand experienced) many instances where tutors went above and beyond to help students in need. At this university, you are very much an individual and treated, respected and cared for like a individual (as opposed to being just another cog in the machine); although contact with tutors is often limited, the tutors do make a concerted effort to keep up with and get to know their students, and most tutors here care about far more than just the students directly in their class (there is a sense here that you can go to anyone for help). Combined with the excellent standard of teaching, knowledge and resources, there's a real feeling of not only the university being world class, but the teachers being the ones who make that crucial difference. However, I think that despite all this, life can still be tough for many here; even if the tutors don't try to pressurize students, you can't be help feel the pressure sometimes (because there's so much talent here, because the courses can accelerate very quickly at times and because many people come here with huge hopes, dreams & ambitions), and even if help is plentifully available, that doesn't mean that its easy to reach out and accept that help on a personal level (I know that I struggle with this because I am stubbornly prideful and independant person). And I think there are links between creativity and mental health issues (as well as creativity and learning difficulties) and being in such a concentrated pool of everything, can be an intense experience for anyone, especially if you're a very sensitive type of person to other peoples vibes and emotions. Everyone here is going through intense learning curves and although everyone around you might seem very adult, we're all learning here, and making plenty of mistakes as we go along the way.
I've no idea what the Glasgow School of Art is like, but these are my experiences at the UAL so far, as honestly as I can communicate them. We're talking about world class universities here and while the UAL ranks in the very top of the boards, I think that when you're comparing such top universities, ultimately its their styles of teaching that really define them. If you're the kind of person whose already very driven and independent in your creative practice, who craves freedom and who wants to live in one of the most exciting and hustling cities in the world, then I think you'd be naturally well off to a very good start at the UAL. But if this is not what you're looking for (for example, you want a more traditional or structured creative education), then you'll probably have a better time elsewhere.
Although they're at opposite ends of the country, I strongly recommend that you attend open days at the universities before you commit yourself to either one of them. You'll get to apply for up to 5 universities in your UCAS application (and it always helps to have a variety), but nothing beats experiencing the vibe, people and campus of a place 1st hand.