I suspect that a lot of them return to the UK, and back to their old jobs as they can't afford to take a year off work, pay a fortune in living costs and do the ATPLs and get JAA qualified.
Surely that's not an issue, as HAI's JAA course covers ATPL examinations and culminates in the JAA qualification, does it not? (i.e. it is a CAA recognised JAA course, not an FAA course taught to the JAA syllabus, as other places Stateside do.)
Still, where'd they all go is a valid question. However, I think every school in the UK I've spoken to has had good things to say about HAI. Most seem to know HAI graduates somewhere within the UK industry, and many have said they'd have no qualms about employing them. (Though many said they'd prefer a bit of UK flight experience, which is one reason why I'm now doing my PPL in the UK, and then hopefully going to HAI eventually to do the CPL, FI, etc. )
Si