Underground heating on both floors – this should be a wet system.
Note that one small area in the upper floor will have to be left free of underground heating pipes, as some items will be stored there that could be damaged by heat; download the heating zones plan here.
Download the full floor layouts here (ground floor) and here (first floor). (Ignore all the details about wiring etc.)
The full set of 20 plans, with dimensions, is here.
Note that, at both entrance doors, the couple of square metres inside the door will be a space for people to take off shoes and wellingtons and put them in a cupboard. That small area inside each door should be finished with outdoor stone flags (matching whatever is used to cover the bridge and patio areas).
Note also that there will be no skirting boards – is expansion an issue; are rubber strips needed?
Polished concrete with a ‘marbled’ look would work well in the main upstairs living / kitchen area and the upstairs hall:
It’s a large, accessible space, and would be handy enough to do. Can’t find exact colour online, it would be a very subtle dark red marble effect. The “creaminfinity floor” here looks well, scroll down, at this link.
For smaller rooms, we were thinking maybe microcement? Apparently, it’s cheaper and handier to do, especially in smaller rooms.
Also, do you have experience of working with underfloor heating? Since the floor and heating go in together, I imagine you would work closely with the plumber, as it would be a water based system.
Priorities are looks and durability – polished and micro-cement, has to be as hard-wearing as possible.
The New Shed 