Finally, an update.
The plastering has been done last week.
I also started work on the outer window, there were still some weak spots around the window, and the thing was not airtight yet.
Quite happy with the result, I already have a lot less noise coming in, seems double glass with an outer sheet of 2x4mm with a safety foil in between, 15mm gap and a 6 mm inner sheet is stopping some noise
The plan is to put a single acoustic glass in the inner wall 8mm/double film/6mm - which is only about 1dB worse than twice 8mm, but somehow manages to get 10% more light transmission.
The window assembly will have slightly worse isolation than the walls, but I'm not worried about outside noise. And leakage from the inner glass into the airgap will be blocked.
We also completely finished the first layer of the ceiling.
Tomorrow we start using greenglue on the second layer !
I'll try to put some pics up tomorrow.
BTW, I also got some acoustic sealant of the greenglue company. It may or may not be better than standard professional grade sealant, but it is a lot more fun to work with ! This stuff is so easy to apply, and when it dries it really does some funky stuff. I also noticed you can also seal really tiny pores with it.