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.
I grew up around this area - it really is a gem of a place. The interior is so cool, with sort of organised clutter everywhere. They have a little garden and they serve food. Its not the best in the world, but the whole experience there is great.