Nottingham has that great Professor Polyakoff bloke from the Periodic Table videos.
Southampton when I looked around it was very nice, a proper campus too. I liked Southampton as a City too.
Bristol has fantastic new labs and is a nice City.
I go to Imperial (going into 4th/final year). Back when I applied I put Southampton as my Insurance because it was my only sub-AAA offer. I suspect most will be asking for AAA, or higher now.
As for advice on preparation for doing chemistry at university, the most important thing to keep up with is your maths. Knowledge of A Level chemistry is not particularly important. Integration and differentiation inside-out is much, much more important. Also converting powers of ten (e.g. nanometres to centimetres) which is simple but under exam pressure can trip a lot of people up. Matrices (which a lot of people who didn't do further maths hadn't done) would also be good to know. Quantum mechanics will be a major part of a chemistry degree, so if you've not done A Level physics then read a bit of background on it (quantisation of energy, how it was proved by photoelectric effect, particle-wave duality) will be useful.