Dropout and go underground. to prepare yourself for the world of a rogue doc, i suggest taking notes on Grey's Anatomy, they pretty much cover the whole A Level spec up till degree level. For extra practice watch this korean drama called Doctor Stranger, they'll teach you how to diagonse the symptoms from just touching the patients, which is a valuable skill that most docs dont have nowadays.
No you do not need Maths, but chemistry is essential if you want to be accepted by most. Try Chemistry, Biology and Psychology, if you want to maximise your chances then Physics. You'll be dealing with maths from the subjects in one way or the other but they aren't as in depth compared to A level Maths of course.