Hi Thomas,
I've just checked back on your introductory post and looked again at the photos there. Totte, had certainly had a hard life and been somewhat abused when you took her on. However, to suggest that it would cost £5,000 to fix the keel is less a serious estimate and more a statement that they didn't want the work. But to be fair to them, even at a fifth of their price, it would still be in excess of the boats likely value with the work done.
Because of that I'd say you have to treat her as a project boat and every potential buyer will have a different project in mind. So I say do nothing that closes down options. Sell her as is! It will be bought by someone with a particular purpose in mind, most likely to strip all the sailing fittings, mount an over large outboard on the transom and use her as a platform for fishing. However, if your sails and rigging are even barely usable, then you've got to allow for a buyer who is prepared to do the work to bring her back into proper sailing condition. Certainly don't try to convert her into a not-quite-a-Pedro with their extremely poor sailing performance.
In short, I'd be inclined to do nothing and market her honestly "as is". That way you have nothing to do to the boat and your market remains open to both impoverished DIY sailors and those who don't really want a yacht at all, just something that floats.