^^ This is a good list.
I'd add that if he has access to your passwords, don't change them until just before you leave, or in your case, once he's safely out of the country. Otherwise he'll just demand the new ones or it might make him suspicious that 'something's going on' (which it is) and he'll double down on surveillance or even cancel his trip.
I second the new bank account, especially if your current account is at the same bank his is or is a joint account. Use a different bank. And do this soon if there is a chance he could cancel your ATM card.
I'm not in the UK, so am not sure, but I think I've seen on MN that if there is a mail redirect a letter goes to the 'old' address to advise of the change. I know there's some kind of domestic violence policies in place to avoid this, but I don't know more than that. I'd suggest you contact the post office/Royal Mail and ask them how sending the verification letter can be avoided.
As far as a Ring doorbell, ours does NOT 'go dead' if you turn off the wifi. It uses 'cellular backup' for a period of time. So you need to be sure that turning off your router does indeed fully disable the Ring video capability. Ours is battery, so if we wanted to 'go stealth' we'd remove the battery. But if you can't fully disable the Ring or CCTV, if he's in a different country, wouldn't it take him quite some time to arrange to fly back (if he even could)? Or are you worried about him calling in friends or family?
As far as mobiles & devices, you can take them to a repair shop to be scanned for spyware and tracking software. Or check with the police to see if they'll do it (ours does if you've reported stalking or DV). If you don't get a chance to do this the day he leaves, get a cheap Pay-go phone to use until you do. Then power your devices down and only power up to access them when you are in a safe public location.
When my friend fled her home, it only took us 4 hours to remove half the contents of a 3 bed 2 bath home with NO head start. There were 4 of us and 3 vehicles so if you can rope in people you trust, do so. Also, trash bags are your friend. Don't worry about packing boxes for other than precious or breakable things. Clothes, towels, toys, bedding, pots pans, kitchen goods, and lots else can be put in trash bags and quickly moved. Granted, her new place looked like a refuse collections point, but she got out super fast. Once she was safely out, she took the time to reorganize and pack things away neatly.
You can do this.