Got a phonecall about 45 minutes ago to say he was able to have his op today after all and had come round. So went to pick him up so he can recover in a nice warm house.
He's in a little box at the minute to keep warm - they've put a rubber glove full of hot water underneath a bunch of cloth and some bubblewrap. Back for a check-up next week. So relieved! Just need to keep a close eye on him the next while. He can go back in his bin cage tonight, as well as a low food bowl etc... wondering if I'd be best putting a bunch of toilet roll in to line the cage, incase woodshavings irritate it. He'll be getting some Carefresh tomorrow I reckon.
Here's a photo of the little trooper, he shall be sleepy for a good while yet I'm sure: