So with the plans for the heavy lifting part of the renovations in place and the builders starting, I went back to England in January to carry on with my life. While the bathroom was being ripped out there would be no sanitary facilities in the house - so no possibility of me staying there.
The builder's first task was to gut the old bathroom, excavate the cave room to add another 1.5m to it's length and increase the height of the ceiling to accommodate people over 5 foot three. Next was to start with the new fittings. The position of the new WC was to remain the same as the old one,thus removing the need to dig up the drains and relay the sewer pipe, while the old water heater would remain - as it seemed to be quite serviceable. Time went on and I was hopeful that by the beginning of March, the house would, once again, be habitable - oh well, nice plan.
It turned out that the builder had basically got a couple of lads to dig out the bathroom, under the auspices of an experienced chappy. In practice it seems that on the days they did turn up, when the weather permitted, most of the time was spent leaning on their shovels. My local spanish neighbour commented that "el gordo" (by which I understand, the foreman) just sat around reading the paper all day. After a radical redeployment of his labouring resources - sacking the old team and becoming an advocate of the old saying "if you want a job done properly, do it yourself" the bathroom started to take shape. About a month behind schedule.
I planned a flying visit at the end of March to inspect the work, wave some cash at the builders and maybe start thinking about home comforts. Since I was still not sure about the state of the facilities - despite assurances that the toilet would be "usable", I kept the trip down to just a few days: the limit on how long I can keep my legs crossed.
The good news is, that when I arrived the builder had been as good as his word. The "bathroom" was just about usable, provided you didn't mind the slight lack of a door, the rough-concrete floor and (as I discovered myself, that first night) no lights.

Though, as you can see the bidet had been installed