I took a look around the site. I'm happy to see they're not trying to get rich off the labels. They're only .05 British pounds each.
It's a great idea but I see a lot of groups that only show one or two bags made. I hope it's just because they aren't reporting in instead of abandoning the idea.
There is the very real issue that pre-made reusable bags are incredibly cheap, I see them at check out stands for only $1 to $2 all the time. With that ease of availability for shopping bags it's hard to justify your time with so many other good causes out there. They might be good projects for things like outreach centers that teach sewing. The students could make them to either use or give away as part of the class.
Rodney