Update if you are interested. First night success!!
Fed them at 6pm
Water removed from 7.30pm
Last trip outside with them at 10pm then both locked in their own crates, in the kitchen side by side.
Went to bed 10.30pm and set an alarm to check on them at 2am. Snuck downstairs - no noise, so I thought I wouldn't risk it and just crashed on the couch. I was expecting to get woken up at any time so had rubbish sleep (not bothered) but it was only when our 4yr old boy came downstairs at 6am that I could hear that the Collie was awake - not crying just playing.
Went in to kitchen to get a massive lovely greeting, straight outside for a wee. He did poo in the kitchen after though - I'll work on that separately - but all in all an overwhelming success - 8 HOURS in the crate, no crying, no mess.
Thanks again for all your inputs it's making a difference here (so far - only night #1!)