I am sure Gateshead is great. But, sounds like the girl is unhappy, critical of her current system, and may need some help before just sending her off to England. (if you are in the US)
First, growing up with divorce situation, plus lack of happiness in school, rightfully or not – she may benefit from a good female frum therapist who will help her gain inner strength and possible an accepting and happy perspective on life, in general.
She may benefit from a smaller school with a dorm to build herself, school with a lot of spirit and hashkafa, but it doent not have to be across the ocean. Many possibilities in the US. Find out about local options. I know a girl who came back from England, had family issues (not her fault, of course), parents were hoping England would be a cure. It was not. She made good friends, and deferred the issues, but nothing went away. I am currently looking to place her ina good home for better role models. I am sure your daughter has wonderful parents, but life is not always easy for a child growing up in a divorce situation.
Good luck