Revise for mocks, definitely. Revising for mocks will really put you in a good position because it will cement everything in your mind and by the time you get round to the actual thing then you will have done a lot of the work already- it will be much less stressful. I know because I revised for all mocks and in class assessments other than english lit (we had no mock for this); when it came to revising for the actual thing, literature revision was so much harder and more stressful than anything else.
Revise for like 1-2 hours a day for a couple of weeks before your mocks and you should be fine. Then do bits here and there in January, revise lots in February half term and after than bulk it up until you get to about 4 hours a day around the actual exams. Most important thing is to not stress yourself out, though, which is what you're helping with by revising for mocks.
Also, this isn't a definitive guide to revision but it worked for me.