Yep. The AP tests would function as entrance exams in to the UK system, essentially. And if your HS doesn’t allow you to study enough math, you should take classes in CC (maybe in the summer) so that that you reach a level where you can get 5’s on AP’s.
BTW, I have heard of Scottish unis giving a year’s credit for A-levels (so that you can graduate in 3 years instead of the usual 4 making it in line with the 3-year undergrad degrees that are common in England), but not of them giving credit for AP’s.