How did your mocks go? Instead of stressing, you should really get down and do the work now (i know that's incredibly difficult to do though).
So I think you should make a few aims that you want to achieve by the end of the holidays. E.g. one past paper for each exam and go through the paper, making notes on topics you didn't understand etc.
And then using these aims, figure out how much time it will take in total, divide up the time in to days. So for example using the previous aim, say that it will take you 16 hours. If you have 2 days left, then do 8 hours per day with breaks etc.
Then stick to your schedule!