How to revise - practice. Don't worry about it now though, just make sure to note down all the relevant dates for when to create a Pearson/UCAT account and when does booking open so you can be there on day one booking the UCAT at a day that is convenient for you. Mid to late August is nice, you give yourself some time to practice for the UCAT without clashing with school, and it gives you time to process your UCAT results and do the research to apply strategically to medical schools.
Ignore people that tell you you need to start practicing for it now. You don't, I'd argue that that is in fact counterproductive. I think anything above two month's prep time is overkill, one month just about right, although you may need more or less time. The key is little but consistent practice. UCAT says the top scorers do 1 hour a day of practice, and only 25-30 hours total practice, which is bang-on the money.
The best practice materials are the official UCAT question banks. If you pace yourself, you shouldn't need any additional resources.