Havard law school is post-graduate, but for their undeergrad program there is no distinct requirements, but only 9% of people get in, and of the thousands of UK applicants, the only ones who get in are those who went to top grammars/independents, achieved 10+A*s at GCSEs, are doing god knows how many A Levels or the IB and getting top grades, top UMS, in all of them, are doing really well at maths and English (they want fantastic standards of calculus), captain every sports team, spend all their time volunteering and have powerful and rich oarents.
Don't be fooled by how good they are, the admissions attitude they have mean they will have a fall from grace soon. Even Cambridge are ranked above them in some league tables.