Catching up with Chemistry after being out of education

I'm starting a course in BSc Chemistry at the University of Reading in September 2016. I will have been out of education for a little while when I start, and am worrying that I have a lot of catching up to do! I'm gonna be surrounded by 18 year olds who are fresh out of their A levels, and would hate to be at a disadvantage.

How should I best catch up, what sort of topics should I focus on; should I just go over the entire A level syllabus?