Spend alot of time hanging out in places like corner shops and stuff eating all the food, drinking and chilling, probaly spend alot of time in video game stores playing all sorts of games for abit.
Then I'd probaly head to London, check out Wembley, take some penaltys and what not. Then off to Houses of Parliament for the day just to see if I can find out who shot JFK and that sort of thing, maybe find some guns to play with. After that I'd head to the Hardrock Cafe and steal a Hendrixs or a Slash guitar and go and play it down in the O2.
Then I'd spend my time inbetween hanging out in shops eating, getting wasted and playing videos and going to famous peoples houses, logging on their computers and seeing what kind of porn they fap to.
Unless of course these mutants are dangerous, that would just ruin everything, if that were the case I'd probaly sit in my night gown playing Football Manager 2010 while quietly weeping to myself before eventaully the mutants find and kill me. My first 3 paragraphs are assuming the mutants are like giant, half bunny, half kitty sort of things.