Those with older kids or teens, try an East End Tasting tour. We took our girls who were 19, 14 and 12 last summer and they absolutely loved it. It's a easy paced walking tour that starts at Old Spitalfields Market, with stops for different food tasting as well as a drink in a pub. It also included viewing of some fantastic street art. Our guide was informative and fun. IIRC our tastings included a bacon sandwich, bread and butter pudding, cheeses, fish and chips, a variety of curries and naan, hot salt beef and bagels and ended with tea and cake. The portions are a good size so go hungry. We got to see a part of London that we probably wouldn't have went to on our own. We ended up going back to one of the curry houses in the Brick Lane area later that week for dinner.
http://www.eatinglondontours.co.uk/east-end-food-tour/