A great place to start the day if you are in South London is Federation Coffee in Brixton Village. The food is great and so is the coffee. This is a very chilled place where you can get both and indoor and outdoor experience (even though the whole place is under the Village roof).
A place that really grows on you, with each visit the Barbican reveals more of itself to you and your bond is tightened. The Barbican Kitchen is great for coffee or lunch, summer hangouts by the ponds, cinema in winter, the amazing Barbican Hall for live music, and don't miss the conservatory.
Audiophile paradise. Boasting one of the coolest looking and beautifully crafted sound-systems I've ever seen. More listening bar than club, it has a low key vibe with a diverse roaster of talented DJ's spinning an eclectic mix of tunes and full albums.