I'm going through the transplant pipeline right now, and I've been told to expect that it should still work, but probably at a lower effectiveness than someone not on a post-transplant drug regimen. I'm really hoping the timing works out so I can get it pre-transplant though.
I'm Canadian, so I imagine it's a completely separate system (for example, I don't know what a "trust" is). I go to my local hospital which has a pretty large nephrology department.