I do Physics and am in year 12, great subject!
There is one guy in my class who doesn't do maths and he frequently gets the bottom marks in the class, I'm not saying that he is bad at physics because he doesn't do maths, but it certainly helps.
In AS, there really isn't that much maths you will have to cope with, I think deriving the ideal gas laws and Kinetic theory are probably the two most complex, but with a little thought and what is really GCSE maths knowledge it is fine.
Don't let this put you off, physics is a great subject that if you enjoy at GCSE, you should certainly do at A-Level, but if you end up really enjoying it at A-Level and feel like continuing to Degree level, you won't be able to without maths.