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 best magazine store in London! MagCulture stocks around 600 independent magazines from all over the world. They always have the latest issue of everything and you will ALWAYS find something you've never heard of before. Make sure you visit on PAY-DAY, as there is a good chance you'll walk away with a delicious new publication.
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.
In terms of materials and form, these galleries offer so much. On an abstract and typographic level, so useful. This is a section of an altar frieze, from the Eye Temple at Tell Brak (N.E. Syria), dated 3300–3000BC. The Egyptian rooms take the tourist weight; these spaces are much quieter and amenable time spent drawing and thinking.
The many book stores dotted along this strip can provide hours of inspiration. Aside from those selling new books, several specialise in second-hand and antiquarian books.