Yep, I was was going to do (attempt!) Math A level, but I found it hard at school that they said that do subjects that you can do best in, that would be better. As it happens, Physics is one of my stronger subjects and I am doing that for A level. However, I am doing Geography and Biology as well.
Basically, don't do Maths otherwise it will be such an uphill struggle. They don't care as long as you get the GCSE and can do Mental Arithmatic.
Good luck mate.