I'm very eager to say RELAX OVER YOUR SUMMER!! I'M NOT KIDDING!! but as you appear to have already disregarded that I won't bother. But really, enjoy the summer. In Year 12 you have to go back to lessons after your exams, and there's more pressure for you to get a job at that point, so the Year 11 summer is probably the most laid-back one you'll have.
But for sciences, as above look at CGP. I think they do them for AQA (definitely OCR), but CGP do two types of guides at AS level. You can get a revision guide (~£10) and a student book (~£20). The student book is like a halfway house between the revision guide and the textbook, and is very un-CGP-y (i.e. no horrifically embarrasing jokes). I used the textbook a lot in Biology, but the student book was essentially my life, I would definitely recommend it.