A beautiful and spacious (outside of rush hour) way to get from Highbury, through east London to south of the river in minutes. The train snakes epically through Hoxton and Shoreditch and opens up the Jubilee Line via the beautiful Canada Water / Bermondsey stations.
The Hayward Gallery in Southbank center has held my favourite exhibitions in London and each time they are extremely well curated. Definitely a place to visit !
Slightly biased as this is where I live, but Stoke Newington is great place to spend lazy saturday / sunday afternoons getting sloshed with friends. There are 10 + pubs within walking distance who all are great places for one reason or another. I'll pick out the White Hart for its huge beer garden...