Stuck choosing between Oxford and UCL because of UCAS grades

You need to check with Oxford about whatever application benefits completing UNIQ gives you.
Yes, you can apply to Oxford now, and add any other choicesl ater.
For your other choices, you need to be very realistic - applying to any A*AA course with predicted grades well grades below that is not going to get an offer.

Thank you for your response, I am not too sure but I’ve read 45% of UNIQ applicants are offered a place, just because the course helps you with making the application and less of an “impossibility” for those who would’ve never thought about it, but not the actual application. I spoke to a friend who’s studying at Oxford, and recommended applying to Oxford and then using my 4 other choices to apply with higher predicted grades in January to UCL etc. Also, I do a EPQ and meet the criteria for Contextual offers so some of my choices are AAB-BBB.

Hello, I am stuck in a dilemma over one grade for my UCAS. My current UCAS grades are AAB, with a B in maths and I wanted to apply to Oxford for Compsci and Philosophy. My maths teacher will not move up my grade because her “professional judgement” is that I would get a B, and my deadline to submit my UCAS form is in 3 days. I believe I have a slight chance at Oxford because I have taken the UNIQ Oxford programme and I have prepared lots for the MAT and believe I can excel in that. But do I instead apply to UCL for compsci and philosophy and try to get my UCAS grade moved up since I have more time to prove I can or should I sumbit my form with these grades and I can still be provided an offer at their entry requirements? (A*AA). My other options are Bath, Bristol, Exeter and Southampton for CompSci. Please let me know, Thank you.

I don't think you would be competitive for either. You would be applying to a course two grades below the standard requirements, with your weakest grade in the essential subject for the programme (namely maths - and UCL specifically state an A* is required in maths or FM). Presumably you also are not taking further maths which I suspect most would be and is probably reasonably expected from students whose schools offer it.
Also consider that CS at those unis in general (aside from Exeter) is very mathematical and focuses on the mathematical underpinnings of the field. They are degrees in computer science, not in programming. If maths is a weakness you may want to consider if a degree in departments which do have a more mathematical emphasis is a realistic choice and whether you would be able to succeed on those courses.
Remember getting an offer then achieving it is just step one. You then need to actually get through the degree with good results - a 2:2 or 3rd from one of those unis isn't going to open as many doors as a 2:1 or 1st from a less mathematically inclined department (or a degree apprenticeship in software development or something).
Unless you are applying to the foundation year at Oxford I'm not sure attending the UNIQ programme will avoid the grade gap issue.

Thank you for your honest response, and I see where you’re coming from. I do enjoy maths and see it as more than just a subject, I just think my grades have been reflected unfairly for this, but I will take into consideration about the different course structures that universities offer.

I am curious to know though, however, how does the grade you receive affect job prospectus? Or is this just for postgraduate courses?

Also what is the foundation year and what does it entail? How does it relate to my course and help with getting a degree?

Generally graduate jobs expect you to get a 2:1 or above (sometimes they may specify a "good 2:1" which usually means an average of 65% or more). With a 2:2 you would have more limited options realistically - many of the major grad schemes at big companies wouldn't be an option so you might need to look for smaller and/or regional options. A 3rd usually won't enable you to apply to graduate roles and you'd realistically be looking at entry level roles typically I think.
If you want to go on to postgraduate study, for a masters usually a 2:1 or sometimes a 1st is required. To secure funding for a PhD realistically you probably need a 1st (+/- distinction or at least merit at masters).
For the foundation year at Oxford I'd suggest just reading about it on their website as it's somewhat specific to them and has particular requirements: https://www.ox.ac.uk/admissions/undergraduate/increasing-access/foundation-year
Essentially it's a preliminary year 0 for students who may not meet the entry criteria for direct entry to the course. For Oxford as per the website it's specifically restricted to students who meet specific widening participation criteria (which you may or may not meet).

I see, thank you. Do some universities have a higher rate of students achieving first/2:1? And if so why is that? Also does the difficulty vary between courses?

I looked at their foundation years and there are some that look appealing such as their PPE course, but I don’t really want to go into a job related to PPE, and I don’t want to do a foundation course for the sake of going Oxford and not doing the subject I love. Thank you though.