At the end of day two ... the shower tray is in. I was planning a moulded non-slip shower tray, but these are proving elusive without a special order so I have gone for a normal one instead and will add a full size non-slip mat.
The only other point worthy of note is that the UFH manifold-and-gubbins are under the stairs, but that a lot of other gubbins is in the garage at the other end, so I am putting in a couple of runs of water pipe in case they are needed later. These will be sealed at the garage end.
Look to your laurels, @Onoff, we'll be done in the time it takes you to choose loo rolls.