Advanced Chemistry 1&2 by Philip Matthews are very cheap (mine cost 1p each + P&P) and are old school A-level textbooks (1992) so cover all the fun bits of chemistry you probably didn't do - hybridisation, radioactivity etc. etc.
Why Chemical Reactions Happen by James Keeler and Peter Wothers is a nice read and is definitely accessible for people planning to go on to do chemistry at uni.
Chemistry³ by Andy Burrows et.al. is a big book which takes you a ways further than A-level.