American High School Student Looking to Study At English University?

I am an American student studying at a private high school in southern California and i am looking to attend University in England. Of course i know about Cambridge and Oxford but those two are extremely hard to get into to. I am currently a junior and my gpa is 4.75 and i have taken 4 ap classes so far. I am looking to study Astrophysics or Physics and Astronomy. My question is what are other top British (Scotland and Wales included) that are easier to get accepted to and are more willing to take full time international students? (ex. UCL or University of Bristol) Any information would help