The best street market is undoubtedly that of Camden Town. From Marble Arch to Camden is not difficult.
First of all, and the most important thing, a copy of the London Tube map, which you can pick up at Marble Arch tube station - it's FREEEEEE!
London Tube map - click on to enlarge etc. . . .
CAMDEN TOWN On-Line
Camden Market Map, Camden Street Map, Camden Bus MapCamden markets, 2008 detailed map of camden lock market, stables market and location of Gilgamesh restaurant and bar. Camden lock and market area street map ...
Camden Market is a day out on it's own - you will not get bored - lots of things to see and do. You can also quickly reach the West End, Theatreland etc from Camden by the Northern Line tube.
Have a great day out in Camden. . . .and. . . .look out for bargains. I managed to purchase a quality leather jacket at Camden Market a year ago for a mere £10 - blimey!