A level chemistry

First of all, you definitely need the OCR endorsed Chemistry textbook. We were given them in school, though we have to return them at the end of the year. I'm not sure if you're doing AS or A2 at the moment so I don't know if the AS books I'm using at the moment will be any help to you.

Also, definitely keep (or get hold of) revision guides and work books from the past year or two of Chemistry. It's really such a great resource because, like it or not, you forget stuff. I've pretty much memorised the Edexcel separate sciences from my GCSEs by looking at my old revision guides (I'm doing all three sciences so this is useful to me).

I like to collect any revision guides for my subjects that I come across, regardless of the exam board. Getting info from other exam boards can actually be helpful to you as there may be some things OCR doesn't cover.

Other than that, find worksheets and set yourself homework.