I've used the one on Druid Street. Can't remember the name. Its on the bit that's east of Tower Bridge Road, in the railway arches. He was very helpful and seemed happy to give me his time even though I was buying a small piece of glass.
Yes, I've used them in the past but they don't have any in stock, pain since they're closer. I never feel too comfortable carrying big sheets of glass around, especially this stuff as it's only 1mm thick.