What does it take to get into top UK schools?

As collegemom3717 said, they care about AP scores in subjects relevant to your course - so your Calc BC score isn’t very relevant if you are planning to study English Literature. If you are planning on taking the IB instead of AP, that’s fine as well. If you’ve completed enough (relevant) AP courses before your senior year, you might even be able to get an unconditional offer.
Your SAT / ACT results are also of interest.