I know that Tesco &c now carry plenty of organic products, but I'm hoping to find a good ol' earthy-crunchy grocery store that has stuff like bulk grains, freshly ground peanut butter, and spices, in either London or Cambridge. I don't care as much about all the dietary supplements and personal-care products that such stores in the US tend to carry as well. I did find a shop on Holborn St in London that has an ok selection of pre-packaged organic nuts, fruits, &c, and vegetarian sandwiches, but they seemed more focused on their body-building/fitness type supplements (a la GNC).
(I know that Whole Foods is coming to the UK but I really prefer not to shop there for various reasons... sorry...)