I buy some clothes online from ASOS They have some really nice stuff on there and some great sales too.
The shops I go to are places like River Island, totally agree with Tenaj, fantastic shop, the shoes are the best, so unusual! I also go to newlook, select, Topshop and also I go to market stalls. I'm not ashamed to admit it either, they have fantastically cheap clothes that everyone always comments on when I wear them. Because most of my friends wouldn't dream of shopping at a market so they're all wearing the exact same clothes as each other from all the top designer clothes. This may sound big headed but I actually think some of my clothes look better than my friends expensive designer stuff