All good boarding schools and colleges in the UK insist that their international students, whatever their age, have a guardian. 

A guardian represents a student’s parents by caring for the child independently of the school or college, doing everything that a parent would do if they were in the UK. Help with travel to and from the school, checking that the child is happy and settled, talking to teachers and house staff, going to the school parents’ meetings, sports matches or plays, offering a happy and safe home if the child has to leave school for any reason: the guardian is there to help that individual child just like a caring parent.