Yay! The hot water is fixed and the house is warm again. Having seen what the plumber did, I know what to do in future, but I’m still glad we got him in. It only cost us £30 to have the work done, so that wasn’t as bad as I had expected.
Just got to leave the wall to dry for a couple of days and then try my hand at plastering, which is something I’ve never done before. Eek!