Retrophotographic have just moved premises and are getting back inline with their backlog of orders, etc. Nigel Dear who runs retro. is really nice and helpful, so I suggest you hang on a bit for a reply! They don't have glycin in their list of raw chemicals but he may be able to source some.
Anton
I believe the only people that make Glycin for photographic purposes is Photographers Formulary in the US. I have bought it from them in the past with no problems. Martin Reed, owner of Silverprint has posted elsewhere on apug asking for suggestions on what people would like them to stock. Perhaps he could be persuaded?
I've never kept any for more than about a week in powder form so can't help you there.
I used mine for mixing up Ansco 130 developer. Once mixed the developer seems to keep working for weeks. There have been a lot of posts on apug regarding the keeping properties of Glycin. Some suggest mixing it with Propylene Glycol. Best do a search.
I've kept mine frozen in my freezer for more than two years. I normally use it to make Ansco 130, but to test to see if the glycin was still good, I mixed up a bit of GSD-10 film developer which contains only glycin as a developing agent. The film developed as I expected. So, in my experience, freezing glycin preserves the dry powder.
juan