So you're all deadly clever then, taking these classes a year early?
You can't do that in the UK. The closest thing to it is if you are in a school which groups kids according to ability, and that's not very common any more. This is a good thing for anyone who's average at a subject, but if you are very good then you only suffer in mixed ability classes. At primary school I was placed with kids a year above me, but there was no way the local authorities would let me go to high school at 10 so I spent over a year learning anything I wanted to (easy to deal with, with only 30 kids in a whole school). Then it took until I was 13 to finally start learning anything new, by which time I'd developed an unhealthily strong independent and anti-authoritarian streak!
I suppose its better to be a geek in the US then. It would certainly be excellent to have to be at university for less time, as there would be less bills!