I did a bridging course for maths ext at the beginning of this year at UNSW. They only taught the content from the HSC that would be directly needed for your study at uni. It's not like your going to cram the whole HSC course in 4 weeks. The tests you do each week are not really difficult but are more testing if you have been listening. I found the lecturers were really friendly and I didn't have any problems learning the content. I was worried before I did it that the bridging course would be a mass cram, but I had a lot less work than other people that were doing more than 1 bridging course.
Hopped that helped, I would have to dig up my old bridging course book to tell you the exact content.