I looked into London. The downside of it is that it is very expensive to rotate in London -- combination of real estate and student fees (Imperial College charges GBP 400 pounds sterling a WEEK in student fees for a rotation, not including rent, which is also a fortune -- total rip-off).
Many of the smaller cities in the UK are actually relatively cheap to rotate in (Cambridge for example-- no student fees, and rent like GBP 30 a week). I've just been contacting the schools directly. Some of them have an online elective application, while others will give you their information if you phone the appropriate person and ask whether foreign students can rotate. Seems to work for me.
