Would I be able to get into a city/MC firm?

Can't say it would be a waste of time, but it would be a massively steep uphill battle, and so would most city law firms.

At the end of the day, you basically need to tell a convincing story. There's really 3 criteria or "areas" that you can use to tell your story:

- Academics. If you're doing great in your courses, the message you're sending is that you really enjoy studying the law. While it may be theoretical and not resemble practice, it shows your direction. Even if you're not studying law, you'd be able to spin it in a certain way convincingly (e.g.: studying international relations, you saw how important international trade is to society or whatever, I'm just freestyling tbh). And of course it's a litmus test for intelligence/capability. Not everyone with good grades is smart, not everyone with bad grades isn't; but that's what some people may assume.

- Legal experience. To have legal experience is to show conviction that this is the path you want to pursue. It makes you a) more ready for practice, and b) less of a flight risk. Of course, good/prestigious names help, but it's really the experience that you gained out of it: what did you learn, how has it influenced you?

- Extracurriculars. I'll include non-legal experience here because it all essentially has the same purpose, especially at the undergrad level. Maybe at a more senior level, if you're transitioning from another industry after a few years, it shows expertise etc, but that's not what you'd have I'm guessing.
Extracurriculars are a way to show your capabilities and breadth of interest. Many things could matter here; commercial awareness, civic-mindedness, public speaking, leadership, entrepreneurship, writing skills, really anything relevant to the legal profession. These need to be substantial; no one will care one bit that you're a member of your law society. But a committee role actually says something about your work ethic, commitment, etc. Customer service/office admin jobs can also be relevant here.

To have the best chance of succeeding, you should try to score high on all 3. The less you have of any, the lower your chances are. Legal experience could in theory make up for average academics, as could extracurriculars. Stellar academics could make up for zero legal experience, in theory. But if you're scoring "average" on all of them, then you as a candidate are uninteresting and there will be people above you in the pile. Essentially, it means you have very little of substance to talk about in your app questions.

Give it a go, you can never say never. And worst case, you'll come out of this with a great insight into the application cycle. You'll have spoken to other people who are applying and you'll have a rough estimate of the benchmark for these firms. Just make sure that you consciously approach this as a learning experience, and make sure to fill in those 3 criteria between now and your next application cycle in 3rd year. Make sure to use this summer to prepare.

But, to answer your original question of whether specifically Allen & Overy is a possibility, the possibility is very very minute. You'll be up against thousands of other applicants who HAVE filled in the above criteria. Then you go into the even trickier things like the fact that A&O and most other high-tier firms prioritise TC recruitment from their Vacation Scheme/Open Day attendees. My advice would be to manage your expectations and look at it realistically. You still have many years ahead of you, so just make sure that for the coming cycles you're more prepared than you are now.

Allen & Overy ask for a minimum of AAB at A-level, which you do not have. Apply if you'd like but I wouldn't hold my breath for it.

I've been thinking about it and I realised Allen and Overay isn't for me, however I know most city firms will require higher A levels but if my degree can't override my A level grades then I think they're being a bit harsh in my opinion. I feel that if I had the experience and the extracurriculars along with a good degree then my A levels wouldn't be that important.