Gang, thank you all so much for your advice as always. Sorry for the slightly short messages yesterday – I was feeling a bit overwhelmed and useless and didn't want to end up in a big old moan! I am so grateful to you all, and am so feeling the benefit of your experience and wisdom. Not least just in the reassurance that it will get better, and that you all went through it too!
Betty is now allowed to go for walks so today she walked up to the school with us, and then down into the village to pick up a coffee. Then when we got home she bounced around the garden for a bit. What a difference it's made! As soon as we came in, she trotted into her pen happily, plonked herself down into her bed and started snoring. Honestly I am so delighted to have been able to get her out and about, and while we mostly just let her sniff and get used to the world, we did a tiny bit of training with her (mostly trying to get her attention when other dogs walked by) and it went pretty well, so that was reassuring.
Had a big chat with DP too and we have decided to focus specifically on three things between now and January: toilet training, demand barking and being left alone for short periods. The idea that we should have those more under control by 2025 has definitely made me feel calmer. We also agreed that, as per your wise advice, I should STOP GOOGLING, as I was feeling very overwhelmed by all the conflicting information. It helped that I saw a friend and her beautifully behaved, gorgeously friendly dog yesterday, and when I asked how she'd done it she listed basically all the things I would never do (dominance training, punishing for toileting in the house, "cry it out"), which kind of made me think that it's harder to actually fuck it up than it might seem and hopefully even if I get things wrong she'll still turn out okay!
Anyway, today I am printing out a schedule and a list of command words, which we're going to pin up in the office and stick to.Taking back control and all that!