Basically you’re aiming for 800 since the material tested on the subject test is similar to what
The 4s will make Oxford etc impossible. APs are so basic compared to what they look for that they expect an easy 5.
If your recommender states you can get a 5 in 3 relevant APs then you may have a shot at universities such as UEdinburgh or Durham.
I mentioned a couple possibilities already, look them up.