ill have a ground source heat pump running the proper water powered underfloor heating (if that's the kind your referring to)
the concrete ill prob do myself to their specifications but ill leave it upto a company to polish
Ed, I can see issues on the horizon if you do the concrete yourself, if the polished finish isn't as you want or expect, then the company will duck the issue by saying its the concrete, we didn't lay it etc
Also same issue with the underground pipe work, if you get a leak or some such 3-6 months down the line who's going to fix it, or pay to fix it ( because when your living in your grand designs house
it'll be expensive & messing to put right)
I'd be tempted to let one firm do all the work & get an insurance backed guarantee (in case they go bump) I know it'll cost more but it maybe worth biting the bullet, for piece of mind