There is not very much that can be done with a high workload except to prioritise them in order of when they are due, grit your teeth and grind out all of the work. But, you need to start to think of ways to avoid this situation in the future.
The most obvious one is to simply do all of the work that you get as soon as possible, rather than leaving it for a particular day. Next, when you revise for a test, make loads of flashcards and mind maps and posters and notes on separate pieces of paper from your book. You don’t have to do all of the above, just choose which one works best for you and revise like you have your A-Levels/GCSEs the next day on that topic. Not only will you probably get a good grade in your test, you will also have things to revise from when it comes to GCSEs/A-Levels; rather than starting to revise a tear before the test.
That way, you have less stress during the exam period, because you don’t need to write out all of those flashcards/posters/mind maps etc. For languages, I recommend writing your own dictionary of all of the words that you have learnt, on top of posters. For maths, you shouldn’t write notes or make anything; you have to just do it. You have to do lots of practise questions for maths. English works best with notes and practise questions. Sciences work best with flashcards and posters/mind maps. History and Geography work well with posters/mind maps. If there are any subject that I have missed in the above list, let me know in the comments section down below and I will be happy to add it in.
How to: School 