I don't think American uni's care much about A-level grades. They have their own SAT's which you gotta take to apply.
(a friend applied to MIT and said the SAT's were pretty easy compared to A-levels though)
I agree with everyone though, you gotta be amazing at something to think about getting an affordable offer...
(Original post by h.b123)
What do you need to do in terms of extra curriculum and grades and what do you generally need to do to study a undergrad course at harvard?
Stellar academics (grades and SAT) are a given, otherwise you're unlikely to get near.
Then you need something that sets you apart. Top level sport is probably the best because it's hard to replicate in a short period, rowing in particular sees a lot of Brits go over to crew for Harvard.
Music is a similar thing, you can't get good in a short time, so if you're a brilliant singer or instrumentalist you can offer something a bit unusual. Though music and academic brilliance are probably a more common combination than sport.
Finally, the 'quick fix', some form of volunteering, the 'personally built an orphanage in Africa then dug the well myself using only a teaspoon' sort of thing. Probably the most common because it doesn't require years of practice.
And a healthy dose of luck probably helps.
If you post on collegeconfidential you'll get a lot more info from applicants and current students.