I did next to no revision because that was what I felt comfortable doing. We did a week or two of working through past papers in class (informal, not exam conditions) in Maths minus however many lessons I missed for music (I had a bad record for missing Maths - it was on all the days I had music lessons!), but on my own I did about half an hour a week or so before the exam just to remind myself of all the techniques (no practice Qs though I did look at Bitesize once and some of the GCSE questions are useful for things like factorisation that their SATs bit doesn't have). Obviously if you listen in the lessons and absorb/remember new concepts well you'll need to do less revision, but just do how much you feel comfortable doing and remember to chase up what you haven't been told!
I didn't use a revision guide myself though we were constantly recommended CGP books. Frankly, I would have rather beaten myself to death with a CGP book than actually read the thing (we got free guides from school for Year 6 SATs - I hated the naff jokes and found the questions badly worded and irritating), but it's a matter of opinion and some people love them. If not, I saw a couple of friends with modern-ish look revision guides but sorry, I can't remember the name!