Charity shops in areas where rich people live can be a great source of quality cast offs. I love charity shopping in Wimbledon Village, and then window shopping in the boutiques there.
There is also a vintage shop, which was closed the day I went:
Graham and Green have lots of quirky interior decorations:
There are lots of lovely places to go for a coffee stop. Boulangerie Paul do the most amazing French patisserie and pastries: