UK Citizens, I need help, what is the best store to order electronics in the UK?

My girlfriend lives in the UK, I live in the US, her birthday is coming up soon. One of the birthday gifts I want to get her is a printer for her computer, she needs one very badly. I can't get one here in the US and send to her since it won't work. It won't plug into her electrical outlet. I want to order one from a store in the UK and have it sent to her. In the US the best stores to buy electronics at is Circuit City and Best Buys. What is the best stores to buy/order electronics from in the UK? What is the most popular store to buy TV's, Stereos, Computers, etc at in the UK and please provide me a phone number and/or website so I can contact them. I can't ask her since this is going to be a surprise. Thanks for all your help. Please hurry.