Plaster Lathe. My old nemesis. Probably with reed or peat for stabilization, so it explodes everywhere once you touch it… Wish you the best of Luck.

Also: napping is important at our age.

As someone who electrically renovated houses without beeing an electrician. If you find an electrician who is willing to work with you: do a full planning of the house. (What lines go where etc) ask them to go over this, and pay them for their time. If all goes well this will cost them an evening or three (depending how many flaws they find in your design). Do the wiring and drilling raw sockets yourself. Buy the top sockets wholesale, then have the electrician make a fixed price for installing sockets and wiring your fuse box , it will be much cheaper.