I had to leave him there :(
The emergency vet said that his bladder wasn't very full but his symptoms of straining on his litter tray and licking his bits lots, pointed to having a very early blockage.
I had to leave a £100 cheque deposit in case I didn't come back..but you have my cat of course I'm coming back. Well, I suppose some people don't. :(
So we have to pick Tigs up tomorrow and take him to our own vets....fingers crossed for him :(