Advice on repeating year 12?

I attended a really diverse high school, but my current college is the complete opposite. That's why I didn't manage to make many new friends during year 12 (apart from my school friends who go to the same college.) I still have another year left, so I could try to socialize more and improve my experience. However, I'm contemplating whether I should redo the year at a different , more diverse place.

One reason for this is that I'm scared that I might not have a fun university experience, as many people say they formed better friendships during school - but if I repeat the year, I would probably be more likely to have a better A level experience - obviously the opposite could also occur and I might end up hating the new college I'd go to. In terms of A levels, I'm a bit behind, but not so much that I won't be able to catch up.

However, there's a drawback to repeating the year – it might prevent me from taking a gap year. If I don't get accepted into university when I apply this year, I could take a gap year and reapply. But if I decide to repeat, it would mean a two-year delay instead of just one.

Does anyone have any advice?