If you want a peaceful day out of the busy city, Highgate doesn't really feel like London. The cemetery is interesting and peaceful, there's a tour of the old half which is definitely worth the money. Karl Marx, among others are buried there.
I love how much you are aware of the changing seasons out of the city; there are numerous beautiful forests around Hertfordshire to go for a run, a walk or have a picnic. One of the best destinations for a day out from London might be Northaw Great Wood. The main entrance is located on the Ridgeway, the B157 from Cuffley to Brookman's Park.
Inspired by Dave Eggers’ projects in the USA such as the Pirate Store in San Francisco and Superhero store in Brooklyn, The Monster Supplies Store in Hoxton is home to the Ministry of Stories: A volunteer run organization, founded by Nick Hornby, to help young people with creative writing of all kinds through workshops and free mentoring sessions. The store is the “Purveyor of quality goods for monsters of every kind” with fascinating bottles and tins containing everything from eyeballs to Zadie Smith’s short story Mortal Terror.
As a keen runner, running through Greenwich Park and on to the river side I see the Thames Barrier, which is not only the worlds second-largest movable flood barrier (after the Oosterscheldekering in the Netherlands) but is also an iconic site on what is fast becoming a recognised stretch for developers including the 02 and Ravensbourne College of Design and Communication.