UCL does tend to rank above King's. I would have liked to apply to UCL but they don't accept Canadian high school students for medicine :(. I don't know much about any either of their post grad courses though. I hope you make the right decision for you. :)
Well done Marie!
I got accepted to King's as well (for medicine) and I will hopefully be living at the Hampstead Residence (and, just like you, no, I did not choose Hampstead because of Coldplay. It's just a really nice area that I will probably never be able to afford to live in again.)