If I could sell it for £1k I would have lost £2k from this debacle.
and you'd be 1k better off than if you did nothing and had to have it towed away for scrap in 12 months time.
Actually I think you might get more than that if you sold it as is. IIRC WBAC have offered you £1200, and they're not known for paying over the odds.
I've seen similar cars sell on ebay for closer to £2k. Personally I don't think they're worth it, but others obviously do.
If you are going to sell it as is, the sooner you do it, the more you'll get. Once it's been standing for months, it'll likely just be a parts pack.
you would have the car you wanted
I'm getting the impression that the OP doesn't want this car anymore. I'm thinking her feelings toward it have been soured by this experience and, frankly, who could blame her for that?
Repairing the car in the long run may be your cheapest option
It could also be the most expensive; this car has all the signs of being a complete money pit. The only person who's going to be financially better off if this car is repaired is the person who repairs it.
My view is that however much is spent on this car now, it's going to be a maintenance liability for the rest of its life for whoever owns it.
If you had to spend £500 for the MOT
Putting this safely back on the road for £500 is fanciful if you're paying someone else to do the work. It's quite a bit more than just a rear beam replacement, and even that doesn't look like it'd be straightforward, given the extent of the corrosion.
Asking the garage that did the last MOT for a quote to make it roadworthy is one way to get a more realistic estimate.
and you still had to go out and buy another car
I think the OP is going to put that idea on hold for a while.
That's certainly what I'd advise. From what I've seen of Bath, it's got a pretty good public transport service, and it's not a car-friendly city. I go there 2-3 times a year, but always by train. It's been 10+ years since I took a car into the city.
Last year, I had to wait at the side of the road for about an hour when the bus I was travelling on overheated and broke down. After about ten minutes, I was starting to feel frustrated and impatient. Then I looked at the growing pool of hot coolant on the road, smiled, and thought how grateful I was that this wasn't my problem.
I walked 100yds up the road and went into a cafe. I used the money I'd have spent on parking if I'd driven to buy a coffee and cake, and sat there until the replacement bus showed up.
Realistically, the kind of car that you could buy today for £3000 is perhaps best left to those who have the ability to maintain it themselves once they've bought it.
If someone without these skills and abilities wants to start motoring, I'd suggest they spend a little more and buy something newer.