As for your A-levels, don't worry too much about it.
I'm sure there's tons of pilots out there who didn't do well at Maths and / or Physics in school and still fly perfectly safe.
I was C**P at maths, trust me! I barely passed it all. Do I now find navigation with all the numbers and calculations the hardest subject? Absolutely. Do I have to study it harder than others? Yeap, but still, I manage to get it done.
Don't worry too much, try to be as good as you can but don't expect to be a bad pilot if you suck at maths, it's simply not true.