I don't take any of your subjects, but last school week I got set about two/three hours of Maths homework, an essay in Media, and about ninety minutes worth of Biology work. That's probably about average for me.
If you enjoy your subjects, it won't get tiring. You will only actually study your subjects for about 8-10 hours a fortnight in terms of lesson time, so there's a lot of flexibility in terms of how much time you devote to each subject over time. For instance, I'm currently spending a lot of free time on my media coursework, but before that I was almost solidly devoted to maths.