In Year 10 your mocks are more about understanding your strengths and weaknesses, than about counting towards something - realistically, they don't mean anything, but that doesn't mean that they aren't useful and important. That means that it's probably fine if you take a break, or cut the workload for a bit... maybe reduce the amount of time you spend revising for subjects that you're already good at. Do something to clear your mind and actively take time out to forget about exam stress. Based on your description of your revision, the danger facing you is more that you'll be too tired than that you'll be under-prepared, because you've clearly done some proper work already. It is GCSE season right now, so I'm not sure but there is a possibility that your exams next year (the real ones) will also coincide with Ramadan. I don't know if this is an option for you, but it really is important that you eat a normal diet during exam season, so I would recommend that you don't fast next year, or maybe fast to a lesser extent. Fasting next year might put your grades at risk, and might make you feel even worse during an already stressful period. That isn't a problem this year, but I would advise that you seriously consider it as an potential action next year, just to be safe.