First of all, any medical school in the US can send you to do a few rotations in the UK. The only reason carribean medical schools send kids to the UK is because sometimes there are limited # of rotation slots in the US. If too many students want to rotate in the US they are sent to the UK.
Choosing to pursue a medical education, being a US citizen, somewhere other than the US puts you at great disadvantage when competing for residency slots. You will have the last pick, so to speak, and if you do land a competitive residency it will most likely be at a community hospital. You will also have to go through the extra hoops of ecfmg certification and spend mucho dinero moving from hospital to hospital while completing you rotations. FMG=lots of headache.
If you really want to be a general internest or family practitioner going international is fine and will get you there, but you are handycapping yourself in the process. Remember, its only the rest of you career so be sure to make a wise deicision based on future possibilities. Nothing in this world is certain and I see no reason why one would choose to jeapordize that for "fun".
Peace
Tooth