Mocks are Seen as non important by many but there are very very vital in your gcse as they get you into the college you wish and if you fall sick for one of your exams and desperately unable to attend a exam your mock grade will be inserted.
So revise for them moderately but don't overwork yourself remember that your mocks don't truly reflect your ability because your exams are nearly a year from now.
I'm not the best to advise because I barely did any revision for my mocks and came out with grade that I'm sure didn't resemble my mock.
I would say do about 2-3 hours a night and your well your way to achieving the best you can whilst enjoying yourself also btw make sure you make a planned routine for what you revise and how much content you cover a day , make it reasonable and keep it consistent and then your a gcse master.