I would ask a travel agent for advice... or do some research on the internet.
I have never been, but I hope you have a great time!
Eat at Garfunkles, it is good food
The Tate Gallery, The Victoria & Albert, a general sightseeing tour
Nandos is good for one visit. Its a chain, so look for a well-reviewed one (google)
Its piripiri chicken with rice/fries: very simple fare and reasonably priced
Ask, Zizzi, Strada, Prezzo: Italian chains, google for good ones
Las Iguanas for Latin (not bad chain)
La Tasca (Spanish tapas and paella chain)
Relais de Venise (theres a website) excellent French entrecote steak, a bit pricey, WEEKDAYS only and dress smartish (all the bankers eat there after work)
Chinatown: some good, most bad
Brick Lane (for curries): most aren't that good
Japanese, Korean, Vietnamese, Turkish and Lebanese cuisine tend to be good (my asian and middle eastern friends say)
Well, if I were going... I'd be planning to spend some time at Candy Bar... and the Oak Bar... maybe at Blush... Thirst... lots of nice places.... wink wink