Today's update:
She is still very bright, eager to eat, pooping well and has a bright red comb.
She is trying to stand and even walked a few steps towards the door (on her feet, not on her elbows!) when I brought food, but she cannot sustain it. She stood and ate for a while, more on her elbows, but she struggles, then goes down and pants. So it looks like it is real physical exertion to do it. I gave her another teaspoon of tuna today. That has vitamin B in it too, so hopefully that's helping keep her fortified and getting a bit more B in her. I am keeping the room dark still - just enough light for her to be able to see where things are and eat/drink.
I am giving 1 tablet of B Complex per day. These are the 100% RDA type, not the super strength. I have ordered some Nettex Power Drops (used to be called Nutri Drops) to give her a boost but they won't arrive until Wed/Thurs.
Tried to get an avian vet appointment - not a chance..... This will be without vet help at this rate. Normally, in an emergency, I would go to a non-specialist, but as we have to stay in our cars and hand over the animal, I am not going to do that as I have no idea how it could go if it was a vet who is using theory and not practical experience/knowledge. Had that a number of years ago and it resulted in a dead hen, so never, never, again.
So, in some ways, Peggy almost appears annoyed she cannot get up but she is trying a lot more - basically each time I go to the cage. By contrast, in the first two days, she just sat there.
I am also now trying to put together a sling for her and then will consider a wheelchair approach with castors. If she needs rehab after this (and once the B kicks in hopefully) then I am prepared to do whatever is necessary to help her get back her movement.
Thanks again to all for your advice and help. Please keep it coming and let me know if I am doing the right thing or if I am missing something out that could help.