I was in similar situation to you thread creator. Year 12 math teacher talked slow, sentances jumbled up, took ages to progress through the syllabus. I told him what he was doing wrong as politely as I could, and his teaching went better. You should try this before self-studying because self-studying takes a fair amount of self-discipline.
If you do end up self-studying, at least try to get a sort of regular guidance. Tutors, smart-ex students, people on BoS, your teacher during lunchtime.. They will make sure you're directing your time in the proper direction.
In my math class what I did was basically the above. I got permission from the teacher to study from the textbook during lectures. When I had problems, i'd go ask him during class when he was free, or during lunchtime. Our school had an after-school homework club every tuesday where there was a math teacher you could ask questions- you can bet I used that resource every chance I got. This all definately gave me an edge over the others in the class, I ended up topping that class (but I didn't top the other class!)