Greenhouse Emporium is a shop retailing eco-friendly products, a cafe, and also a retailer for many environmental home-improvement products (insulation, heating/cooling systems etc).
The cafe is great - they do lunch on weekdays which is mostly rolls and cakes, but all are fresh and tasty, and do all-day breakfast on Saturdays (which is both inexpensive and delicious). Their coffee is always fantastic, and you get a discount if you bring your own cup (and if you haven't already got your own, they sell 'Keep-Cups' which are standard-sized reusable take-away plastic coffee cups). Service is always friendly and the atmosphere is comfortable and relaxed.
The range of environmentally friendly products is diverse, the prices are reasonable and they always have new interesting things. The only negative - there are not always staff available to provide assistance in the retail part of the shop, although you can pay for purchases at the cafe.