Nice work Mick!
Are you a sparky by trade?
I might give you a call and see if we can work something out. At the moment, part of the service level agreement I manage, Elecraft do all our testing and tagging. But things can change

Also, I'd suggest cold calling a heap of places like schools, child care centres and kindergartens. Most people don't understand the reasons for RCD testing and appliance test tagging on a frequent basis.
One thing though, you might wanna mention something about identifying nuisance tripping in your thing about RCD's!