A levels adviceWatch
Most people find 3 A-Levels more than enough work, and Maths, Chemistry and Biology are quite content-heavy and difficult subjects. So adding on an AS plus 2 other mandatory courses, I think you will struggle. Obviously I don't know how you cope with workload or anything like that, however based on what you've said I wouldn't recommend taking all of those courses.
The first couple of weeks are pretty easy going. You won't get a full idea of the workload until you get a couple of months into the courses. You should speak to someone at your school and ask for their advice.