Before deciding, I would talk to a few graduates of Access course because they cover quite broad areas and involve a lot of study, you only have to read the posts on here to see how much. Please don't take this the wrong way, but it doesn't sound from your education history that you are particularly "academic" and you might find an Access course too much of a struggle, which wastes both your time and money and gets you nowhere.
It does sound like you have an excellent skill set and portfolio so use that as your bartering tool and try to get onto a Foundation Course. There you will also receive academic and one-to-one support if you are deemed to need it. I teach at a college that does recorded arts and theatre, and we have plenty of graduates who wouldn't have got onto or done well on a full degree course, our course is very practical based. Plus we screen for learning difficulties which often people aren't aware they have, they've just assumed they're not very clever. We have one graduate, who passed with flying colours, who discovered she was dyslexic but had no idea! A Foundation course will primarily be doing what you love most but be aware that with any FD or degree there is an element of theory and plenty of written study and if you don't keep up with this you will fail the course no matter how great your films are, because every course has to satisfy the conditions of its assessors and that is done done through written work. Ours is a two year course after which you can apply to another university to do a third year and convert your qualification to a full BA. The first year is a simple pass/fail, the second year you obtain distinction/merit/pass/fail based on your second year module marks and the opinions of your teaching staff.
I would have a look around for a few colleges that interest you, phone their admissions team and ask questions such as minimum entry requirement, go to some open days and see if you like the creative environment and equipment used, ask the current students what the practical to theory ratio is like and what they enjoy/dislike about the course. Find out too what their student support system is, will you get help with the theory and written side, these courses realise that some people are exceptionally talented when it comes to physical arts but aren't necessarily going to be that great at writing essays.
The quickest route to uni may not be the best, especially if you are not ready to cope with the demands of full-time study. With a portfolio behind you, do you need to go to university or could you get in with a media company on a low position job and prove yourself to them? What do you hope to gain from being at uni?
One other thing that I will mention, our students often complain how basic/old our equipment is, having expected everything to be state of the art. There is a reason for this: most jobs our new graduates (and old) will gain will with low budget companies who do not have access to state of the art technology, but the same old stuff we teach on or be freelance having to provide their own equipment within their own budgets. It makes a lot of sense, if you can use the old stuff, you can usually figure out new things very quickly. If perchance a grad ends up somewhere with something a bit new and exciting, most of the companies who sell the products offer staff training courses as an incentive to buy. That said, some uni courses have all SoA equipment in a bid to attract students by dazzling them with technology, but for the reasons I've explained, it really doesn't benefit the student at all.
Good luck and I hope you find the right direction for you!