Time for an update.
Things have been a little slow, my architect has let me down badly & after 3 weeks of chasing finally let me know he couldn't get any labour. I ended up employing a local mason who wants to do the job on his own & he's turned out to be an excellent worker. The crack in the floor slab was dug out, then a coat of cement epoxy & then filled with cement. We've had to leave it for 2 weeks to dry out thoroughly before applying a coat of epoxy sealer to the whole floor. The sealer was applied today, evil stuff, it filled the house with fumes much to everyone's disgust. Tomorrow we start in earnest with the remaking of the stage & seat riser. In the mean time a few pics of what's been happening.
The HT room bare waiting for the crack to be chipped out. The crack is visible as a light brown line on the left side of the 1st pic.
The crack chipped out.
The repair complete waiting for it to dry out.