I had heard there was a branch in the centre of London and in fact there are a few dotted around now. The stores in the USA are usually in a large purpose build building and is enormous by British standards. By contrast this store in Capham Junction, takes over three small shops with adjoining doorways and is subsequently quaint and lacking in space.
I was glad to see a good range of supplements but I noticed an absence of Stevia, the natural 'sweetener' that in the west we aren't supposed to call a sweetener, because of the hold of the pharmaceutical companies on the governments of USA and European Union. In both the USA and Germany (I don't know about other countries, you can buy the product that calls itself a supplement. The slogan (to get around the rules) is 'Don't sweeten your drink, supplement it.' However it's not to be found anywhere in Britain, which is a shame because it doesn't effect blood sugar levels (and other problems) like other natural sweeteners and doesn't adversely affect the brain like all artificial sweeteners.
After we had visited Southside House we came upon Le Pain Quotidien in Wimbledon High Street. It was a lovely place. There were quite a few families with young children, and the food was delicious.