Being an East London boy at heart I am partial to an occasional fix of café culture. Pellici's has been running since the start of the last century, to which me, my father and my father's fathers have all enjoyed its mix of tasty Italian/London grub and energetic atmosphere. If you're visiting, make sure you drop by, as it will provide a valuable, forever-depleting education into what East London is really all about.
Also the Queens back garden, these beautiful grounds are great for a Sunday stroll to see the pelicans or to feed the squirrels. Duck Island Cottage is worth a look too, a idyllic little cottage situated in the grounds which was specially built as the bird keepers home.
I go to the Heath every weekend (often via the wonderful Waterlow Park which skirts Highgate Cemetery) and during the week too if I’m working from home; it helps to put things in perspective when I’m thinking about my work. It’s great in the summer for obvious reasons but I love it the most in autumn and on those rare days it snows so much London grinds to a halt (which doesn’t take much). Everyone heads up there to make giant snowballs/cats/creatures and surf down Parliament Hill on anything they can get their hands on. Grown ups turn into kids for the day. My husband and I made this snow yeti last year, it was sad to leave him behind but he soon made friends and even made it into the Camden New Journal.
I grew up in the countryside, and if you're ever in need some instant escape from the city, this place is like a time warp. It's a huge space full of over grown mausoleums and graves, feels like a movie set. They also do tours.