If you have a couple of hours to spare in London and no idea were to go, here a relaxing suggestion: Victoria Park. Known as the "People Park", Victoria Park is one of London's favorite outdoor spaces.
Lots of festivals in the summer time and fireworks displays in the autumn. It has 3 huge lakes and is well known for the original landscapes.
Don't forget to stop by the Pacilion Café where you can try a flat white and a cinnamon roll!
If still thirsty, don't forget that Hackney Wick area (very hipster-ish) is near by.