I have put sheep wool insulation in between the rafters. It's pricey, but very nice to work with. Softer and less dusty than mineral wool, and makes the whole building smell of lanolin. I have used 140mm thickness, and the width - 370mm - is perfectly matched to my rafter separation (400mm). I held it in place with bale twine (blue, in picture) until I could get the ceiling lining boards in place.
The ceiling boards are 9mm plywood. They needed very careful marking and cutting around the ends of the roof overhang lookouts.......
Then it's the same again around the walls to seal the gap between the top of the wallplate and the ceiling.
I've put some 50 x 75mm battens on two walls hung vertically, sitting on the floor and screwed to the baseplate and wall plate. I am going to need to fix extensively to these walls (counter, shelves, cupboards etc) so am giving myself lots of support options.
I've had a problem with my roof design. In heavy rain, water drips from the front edge of the roof more or less where I expected it to. There will soon be a gutter in place to catch it. The problem has been that some water runs down the steel brackets that hold the edge boards in place, onto the rafter, to the bottom edge of the rafter and then along the edge until the wall plate, where it collects in puddles and drips. You might be able to see this in the photo below, where there is a small drop of water on the extreme right of the bracket.
I have been along the front edge repositioning the brackets to slant downwards, and I think this has cured the problem.
Clay: I have had a large excavation going on at the top of the garden to dig clay for the internal plaster. It almost passes the clay tests, and I might be able to use a proportion of it, but I have had to conclude that, sadly, it's just not sticky enough. So I have borrowed a twin-axle trailer and headed for a quarry in West Norfolk where they will sell you some. I've got about a ton here:
I've made a pond with tarps and bales.................
filled it up with clay, and covered it to keep the leaves out.
Windows. In the last few days, I have collected my dg units for the windows and got some of these fitted. Suddenly, the outside is beginning to look like a finished building. It's also much lighter inside without the tarps covering the window apertures.
This week, I have been working on the doors. These have already been hung, but I need to put a cross rail in , fit the glass units above and fill the panel below. The cross rail is made up of the 70mm section of door that I cut off the bottom when I was hanging them.
Final photo in this post shows the glazing completed and the bottom panels in the doors fitted. I expect to cover the door panels with thin plywood both sides for cosmetic reasons.The photo is a little dark, but you can also see a new fascia and boxing in of the eaves, which is complete to both sides and the front.