Maths, biology, psychology and English lit. Maths and biology for the science-y aspect of things. English for the essays.
Have you looked at any universities yet? They often list essential or recommended subjects. I'd say sociology is too much of a 'soft' subject to take, but if it really interests you then go for it.
One of my friends got an unconditional offer to study psychology with: chemistry, history, maths and psychology at AS.