Hi Sheelagh,
I was lucky enough to be chosen to home a rescue TT 18 months ago. I had contacted my local rescue co-ordinator. You'll find details of rescue co-ordinators and breeders on the
Tibetan Terrier Association website or call Geoff Cherry the secretary of the TTA on 01582-579850. He should be able to point you in the right direction.
I hope you know what you're letting yourself in for :D They're not always the easiest of breeds but I love them. There are a few TT owners on this board. If you want to ask anything feel free to e-mail me (click on my name for details) or register on Champdogs (it's free).
Good luck,
Dot