Richard H beat me to it.
Definitely brush up on your electrics. If like me it is a subject that bores you rigid and baffled you at school, then I'm afraid there is plenty of it in the a/c systems syllabus.
The rest of the maths and physics is all very basic stuff. All this talk of algebra and transposing equations is little more difficult in reality than rearranging the figures in simple formulae (like speed/distance/time calculations) depending on which one you need to know. Any trigonometry is equally simple (basic right-angled triangle stuff), as is the understanding required of gas laws and Newtons laws. All the mathematical calculations you are likely to use are all pretty basic and nothing particularly complex.
A quick brush up over a week or so with a GCSE revision guide is more than enough to get you into the frame of mind for the studying. Forget that A-level sh1t.