I'm so sorry to hear that. Of all the challenges of keeping an older car on the road!!
Firstly, I wouldn't mention it to your car insurance at the moment, either. If all else goes to shit, that might be your last option.
Following an incident many years ago, below is the legal advice I was given.
Home insurance usually has a Public liability element. (Ridge tile falling through next doors conservatory roof etc, walls collapsing, er ahem)
The most important thing is to establish your neighbours liability. Make a case that it is her wall. Look at your deeds that indicate which fences/walls are maintained by whom. Even better if she has had this wall built herself. (We don't know if this wall is a garden wall, part of her house etc.)
Once it is as clear as it can be that the wall is hers, put it in writing to her that you consider her (personally) liable for the damage to your vehicle and the clearance of the site. Tell her you are preparing quotes for the repair of the car. A good idea to start the ball rolling on that right away.
Go for her throat and make it sound scary. Put the evidence that it is her wall and her responsibility in the letter. I know you consider your neighbour reasonable and that is great, but she will not be making the decision on whether or how much to pay. The people who will eat polite guys for lunch. If it was me, when I hand her the letter, (addressed to her) I would apologise for the tone and simply say, I don't know who your insurance company is, so this comes to you in the first instance. (It is so easy to forget that despite insurance and the idea that direct line etc will sort it out, it is us that are liable. If she is not insured, your can sue her for the damages.(Hopefully it won't come to that.)
What is likely to happen is she will speak to her insurance company and they will then communicate with you. Then the negotiation begins.
As has been said above, take lots of pictures of the car in a damaged state and sort out some ones of it looking at its best. Gather together copies of work done, monies spent etc.
Because this is a public liability claim, I'm not sure if the concept of an item being "written off" is in play. I know for Car insurance it is, but stop to think about it that is a pretty disgusting concept.
I think I would be taking the tack that it is a modern Classic car that is not easy to replace and should be returned to its previous condition.
Finally, this is a stressful process and sounds like it is effecting your ability to work. Not surprising perhaps that some people decide to let it run its course, then take the cash settlement. That is your call.
Good luck.