Go to Brick Lane for a Curry - Aldgate East tube and ask for directions, it's a 30 second walk. There is something like 80 Indian restaurants in this small street. Also close to St Pauls, the City Of London (ie old walled city, now the main financial district).
Tate Modern is always wicked, right now their main piece in the turbine hall involves sliding in a twirling tube down five floors.
Man, so much here, I can't think of a thing. Just chuck yer map away and start walking!
Enjoy, and welcome to our city.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz