Living in Central London, venturing to Greenwich Market was something of a day trip. Catch the Docklands Light Ferry from Tower Hill or Bank, or take the Jubilee Line all the way out to Canary Wharf and transfer to the DLR.
Greenwich Market was a cute little market generally in a covered area with the typical market fare—books, antiques, arts, and crafts.
Nearby there are a number of restaurants—we always ate at a noodle place where most of the dishes were £3 or £4!
While in Greenwich, you should definitely stop by the Royal Observatory.
We really loved going to this market as it seemed as if you were still in London but away from the hustle and bustle of the city.