Ta everyone...it's really good to have somewhere to slink off to.
The insulation is 4" thick and was used for all walls, the ceiling and floor...there was a spare slab so I had it cut to fit in the window space...it's removable, but I leave it there anyway. I had two fire doors fitted as that's where a lot of sound can escape.
Came in under my total budget of £5000...but that included everything...paint, furniture, curtains...even the spitfire! That was £30..it once hung in a pub near Dumfries. Met a lorry driver on a deserted industrial estate in Carlisle to pay and collect...and when his lorry driver mate turned up too, I thought they were going to turn me over...but they were genuine enough...or perhaps didn't fancy it much. I was tired and needed a shave
Building work was all done above (plaster) board...appropriately certified and with Council inspection and consent. Desk and chair were £140 and the globe £10.50.
Yes...a Scarlett Solo, VC...works great and is nice and compact too.