So I'm not done yet but in the process of bracing the roof, the superfoil is 99% done and I've since filled the apex with 25mm Jablite. The ceiling will also have 25mm Jablite with 5mm ply (as will the two apex).
The floor will have superfoil with Jablite above and the walls will have polystyrene backed plasterboard. Once it's done I'll post the finished photos (I know the carpentry work is a bit Heath Robinson but it'll do

)
https://i.postimg.cc/QMt7NHL7/IMG-20241019-WA0003.jpg