Thats basically A levels.
But, hopefully it gets better after this. Basically, try to do most of the work you can in school itself; any free lessons or lunch. Then, maybe do courseworks during half terms (assuming you can get teachers to give you some kind of pointers in advance) before hand so you dont have to do that during school hours. If there is time during half terms, make advance notes as well...
Timing will still be a issue, but it isn't that bad. Reducing sleeping time and coffee should help out with the timing.
And if possible try to have one close friend who is in most of your lessons and studies. You will be surprised how much it helps to talk things to them about it. Complain about the tests, notes and then get back to working again... it helps get the stress out.
If you think there is too much to do , and dont know where to start then dont think about all of the subjects. Just think about one subject and take on just that one subject, deciding to finish everything on that subject within x amount of days.
Then do same for another subject. This seems to work for me....