I would head over to the GAPAN site for more information. They do testing too every now and then. Worth a look.
Find out what is required for a Class 1 medical. The main gotcha's are colour blindness, being too long/short sighted, diabetic or significant hearing issues. If you know you're clear, fine, if not, get those items checked out.
A levels? Well, as you'll be competing with a squillion other newbies, then probably a good idea.