Not a commuter but have had them on the jump seat quite a few times...
expect to become familiar with the Bath Road hotels. Prices are coming back towards normal, but are still higher than they should be. There are deals or airline rates out there. If you have friends / family / digs you can go to that's probably better.
There are whatsapp groups for commuters - usually one for each common airport (BFS/MAN/GLA/EDI etc).
If you're SH, it'll be tough to start with on a junior roster. Swapping will be your friend. LH is probably easier (as most LH departures are after the 1st inbound domestic wave I think)
I won't publicise them here but there are various apps & websites you can join that will make your life easier - you'll be told about them on day 1 I'm sure.
A respectful, polite text or crewlink message to the captain operating the flight you're hoping to commute on usually guarantees a seat somewhere on the aircraft. Just ensure you take account of their pre flight rest before hitting send...
Good luck & welcome to the madhouse!