Not the most exciting place inside, but a lovely rooftop area which not all that many people seem to know about, 2 mins walk from Old St station. If it’s packed then The Red Lion is just up the road.
The St Bride Foundation is the home of the St Bride Library, an incredible resource of printing history, in the form of books, printed ephemera, and tools from the trade. It also hosts many fantastic talks each year – check their website for details.
An unassuming glass door on an otherwise plain facade hides a cavernous space, with high ceilings and huge sliding partitioned walls producing excellent exhibitions in a space you'll want to go back to.
There are many great parks in London to choose from, but Hampstead Heath is by far my favourite; a lido, Parliament Hill with a great view of the city, ponds, woods and plenty of space. It’s a great place to hang out in the summer, but also presents a lovely walk in the winter. Address: (As it’s so big obviously it doesn’t really have a specific address but there are 2 main entrances) Entrances by Gospel Oak or Hampstead Heath Entrance.