Say an ad for Immerse summer school at Oxford and Cambridge. They are extortionate, has anyone tried them despite the forbidding cost? Are there summer school alternatives that are less commercial? Ds is really into science, he wants to be a doctor and we thought doing a summer school programme might be fun and stretch him. The social side would be amazing too. But we could never justify paying 5K for 2 weeks summer study 
Are there any other options out there?