Just read the novels for english and take notes on them. If you want, go through the coursework and familiarise yourself with it. I don't think going too far ahead is going to help because once you start classes you'll more than likely begin to slack off and you'll end up at the same position as everyone else. You say you'll have the motivation now, but like most of us, it dries up pretty quick (atleast for me it did).
During the year I'd do checkpoints questions at the end of every topic, maybe go through a couple exams and do the questions on the relevant topic. Just familiarise yourself during the year with the type of exam questions that will be asked. The best thing to do, like others said, is to study during the year and gain a good understanding of everything so that you don't have to cram during the exam period. I probably should have listened to my own advice though...
Also, don't blame the exams. History is history, there really isn't anything they can make up to fool you. I was getting A+ all year in revolutions last year and choked on the exam too, ended up with a 35. It was my lack of studying and my belief that my sac marks would be a reflection on what I'd get for the exam that caused me to choke, not the exam.