Is external wall insulation an option? Much less obtrusive than internal and has added benefit of incorporating huge thermal mass of the walls.
That, plus a couple small woodburners, some MVHR and they may not need any wet CH.
Best with new windows at the same time. Won't be cheap though.
That, plus a couple small woodburners, some MVHR and they may not need any wet CH.
Best with new windows at the same time. Won't be cheap though.