Always pick subjects you like, because in the end you will do better.And scaling will always play a part in people's choices; I would say that if you are equally good at 2 subjects and can't choose, pick the one that scales better.
lolwtf.Oh, and my science head teacher also said that you need 4 units maths to be able to cope with Physics.
I can understand if you need to know Mathematics (same concepts really)My school only allows you to do physics if you do mathematics
That is BOS restricitions.My school doesn't have any restrictions; the only restriction is you can't do Senior Science with any other Science, other than that, you can pick whatever combination of subjects you want.