Are you serious, man?! Play games (and beat them), talk to people, surf the net, read manga, listen to tons of music, make illegal downloads, watch anime, sleep!!! And this is all the things you can do while still in your house, and there's even more you can do while in your house that I didn't bother to list. You can also go out and there are many activities you can partake in, like sports or just hanging out in some place you like. You live in like, England. That's a place not called Iran. That's a place full of interesting places to visit. It's actually worth it to go out.
I never ever understood the sentiment of "not having anything to do in summer" and for good reason: it makes no sense! I mean, I live in Iran and I have a slow internet and it's really not worth it to go out (even though I'm in the capital city), but I enjoy every second of summer. You guys all live in advanced countries, you should make use of and appreciate what your country has for you. Seriously, you're not understanding how lucky you are.
I mean, unless you have psycho parents who monitor your every activity and limit everything you can do or live on the streets, you really shouldn't have a hard time finding things to do.
As for the topic, I have no idea when my school will start.