4" Kingspan (on inside) all external walls with studding and air gaps to the plaster board.
2" in all reveals up to the window and door frames.
9" minimum Kingspan in roof/top ceilings also with 4" rockwool were possible
2" Kingspan under floor tight up to the boards, plus 4" rockwool in places
All sealed as far as possible with sticky tape, foam, mastic as far as possible.
All wiring/plumbing inside the external shell with no holes through as far as possible.
Also we burn all waste wood, sawdust, cardboard in two multifuels for direct heat.
Heavy curtains and /or heavy roman blinds to all windows and external doors.
Draught brushes to nearly all the doors.
Extractor fan over cooker not to outside but recirculates through fat catcher grille and carbon filters. n.b. you can wash these in sugar soap solution instead of replacing them.
Thick underwear. and down jackets as required.
Try to use the microwave more.