Joe, take a break on the Sunday or something! You CAN'T work every day in the week, that's extremely difficult for anyone who doesn't live on Pro Plus! A 6-day week is too much for most people! I only work 5 days a week!
Enjoy your youth now, you've got 60 years of working life ahead of you yet. DON'T throw away the best years of your life, you'll regret it!
Even if working that much means getting 10 A*'s, is it worth that? The stress and effort alone could break you easily! Even if you get top marks, what will you do with it? Go to college? Sixth form? You'll end up needing to go there anyway for qualifications that have some value in ten years time. College does not need As and A*s. I doubt sixth form does either. Chill, relax a bit. Otherwise you'll end up doing what I did a couple of times and lose it. I regained it, but it's not fun stressing over work or education. Sundays are rest days, utilise them! When you start working, especially in a customer service industry (rail, catering, transport in general, retail, many more besides), you will need to work them sometimes at the least.
In any case, why do you need the extra hassle of work on top of education? Your parents shouldn't let you do so. 6 days learning, 1 day work. Where's the rest? At night whilst you are sleeping, you say? That's not enough! Trust me!
Free time should be just that, free to do whatever you like. If this means spending a few hours bussing around London, popping down to the local station for some number crunching, doing some line bashing, or even just hitting a pub or restaurant for a nice meal, then why not? It's your time. Utilise it well now. You DON'T want to end up in 10 years time thinking about how you wasted so much time. I'm already at that stage. I've wasted 2 years already in failed Higher Education courses. Don't do HE unless you're really committed to it, I wasn't. As a result, I work in catering. You can probably guess I'm trying to get into something else.
If you're still awake, take this if nothing else from my post:
Keep some free time for yourself. God's given you a life, live it.