Hi,
I'm currently on the brush up course, it is very intensive and the amount of work to get through is huge so do as much as you can before hand. But as has been mentioned Baz will sort you out, he's very very knowledgable dosen't mind going through things you don't understand.
He gave us feed back exam 5 today!! which should keep us busy. You deffo need a really good working knowledge of the whizz wheel as it's used alot. Good plotting is a good point too, there is quite a lot of plotting work to do on the course.
Hope this helps
John