On a hot day there is nothing better to do in London then go for a swim in the Heath ponds. You get completely transported you out of the city as Hampstead feels like being in the countryside except you're in central London?!
Lots of traditional charming country pubs around the area, but it can a bit hit and miss. A really friendly one with amazing food (and a unusually large veggie selection…) is the Beehive in Epping Green; close to the Great Wood. It's friendly enough you dare going there by yourself with the paper and are not at the mercy of local rubbernecks ("the rubberneck" = person who stares at strangers without any sign of guilt)
The most special and charming cinema (probably most deprived too) in London. A place to catch a classic or a new release. You can get a lifetime membership for £50, weekly £1 member screenings. A place where staff are as passionate about pictures as its visitors. A must visit for movie buffs.