Yes it's unfortunate but nothing lasts forever. I have recently uploaded my wagon and carriage models to Train Sim Safe House - https://tsforum.forumotion.net/ - as I have assumed that UK TrainSim will slowly wither and die!
Just sent them a direct email stating that I would like them to either activate my account and provide me access to the file library, or to delete the account credentials I used to sign up for the site. Not holding my breath about getting a response, though I really do find it quite s****y that they would not bother to stop people from signing up, and instead let dozens of emails and personal information just accumulate on a server/site run by an individual who doesn't even want it anymore.
Sighhh....well as I said before, thanks to everyone for your help, and here's to hoping that the files on UKTS somehow find a away to survive its inevitable demise.