A rather large project: My house

Yep, already working on that. Rebuild costs are relatively straight forward, somewhere between £900 and £1500 psqm depending on spec and how much I do myself.

Do you have the time and inclination to do a lot of the work yourself and as you have gathered its like opening a can of worms as you won't know what something costs to repair once you delve in to it.

Well I'm happy to do some of the work myself, but I can't do any of the structural work, but I can do a lot of the internals (obviously not electrics etc.), but there is a balance between doing it myself and it taking longer but a bit cheaper compared to concentrating on earning money and getting a pro to do it

Me personally, I'd bulldoze the house and build something eco friendly perfectly insulated blah blah blah tat will last years and once done, enjoy it maybe even using some of the old stone in places.

That is of course the sensible option, but loses the character of the house