My fairly standard loft (didn't have plastic cladding or windows I guess) cost about £55k all in (including party wall, building control, ensuite, tiling, etc but excluding furniture, carpets, decorating,) in 2018.
I had a few quotes (from all-in-one companies) and they were broadly similar.
This is broadly in line with what I've seen heard 25-30% increase in cost for building across the last 3-4yrs. So 55k > 70k for fairly standard spec (but not back of a lorry) job.
My fairly standard loft (didn't have plastic cladding or windows I guess) cost about £55k all in (including party wall, building control, ensuite, tiling, etc but excluding furniture, carpets, decorating,) in 2018.
I had a few quotes (from all-in-one companies) and they were broadly similar.