I've got an offer too, I'm coming from Marylebone girls so using that as a frame of reference as that sixth form is mixed too. I would say that your probably quite a lucky group, boys get a lot of friends really easily as pretty much all the girls want to be friends with a guy. The younger years are never really bold enough to do anything, maybe a few giggles. I think there was once a letter sent to a sixth former from a Year 9 but he didn't really care and the girl grew out of it. Overall, you'll probably find making friends easier than the girls so have fun.