I am currently in Year 12 studying Maths, Computer Science and Business Studies. My plan after A - levels is to do a Computer Science degree. However, I have found that i only like some parts of the course and the parts i dislike i struggle with in lesson and in exams. I am now thinking of dropping Computer Science for Accounting as it is another promising field i might go into.
I think you need to take some time think about your interests do some research and then decide what you (think you) want to do for a career, then figure out what degree best suites that then decide a level subjects. It sounds like you dont actually know what you want to study and are just looking for popular subjects. You might as well pick a degree on something your v passionate about, if you end up going into accounting as the degree is not a big deal for jobs in that area.
Also studying a subject at Uni is very different to at A level.