My understanding is that medical schools in the UK are pretty hard to get into. From what I understand Ireland is a better bet then the UK for American students. Some schools in the UK reserve a select amount of seats for international schools. Most of which are for students from countries without medical schools.
Matt, you are certainly right about British and Irish med schools. However, the two med schools in Dublin have for years been actively courting a small number of American students. A cynic, my guess it is for the money, not to promote diversity. I think I recall when Maggie cut their budgets, UK universities and presumably med schools could make up the difference by accepting foreigners--like Americans--who, no longer subsidized, could afford paying full fare. But I don't recall any exodus of Americans to the medical schools.
I studied at Imperial for one year as a visiting student. Imperial College is fabulous. It has the best resources I have seen anywhere in America or Europe (yes, that includes Harvard, Hopkins and certainly Cambridge). St. Mary's Hospital and Charing Cross Hospital (Baron's Court) are among the several IC hospitals I visited. ICSM also has the newest cutting-edge techhnology. And, penicillin was discovered at Imperial! Unfortunately, they do not accept American students since we have plenty of Medical schools in our country.