Electric film underfloor heating and solid wood

[st3ve]

I have read that solid wood floor is a no-no due to the heat build up in a conservatory. In my north facing conservatory (17m2), however, I won't have that problem I believe, so solid wood floor seems OK.

OK now introduce electric underfloor heating.

Is solid wood still OK?
Do I need to use a particular type of heating matt? eg Snaked cables in a gridded matt or film type? I will have piano and other heavy-ish furniture (ie NOT cane) in the conservatory.

One floor fitter has said that wood floors should be nailed down, but that won't be possible with the electric matt underneath now, obviously!

Can/should the wood be glued down instead and if so, do I need to protect the heating film/matt first?

Could I encase it in ?pva! or something first then glue to this rigid surface?

The conservatory floor will have an insulating sandwich of board and polystyrene or similar (Anglian 'CosyFloor') over the concrete base.

Finally, any thoughts on how to employ the electrician and floor laying guys - who should run the show?

Thanks for looking and any thoughts gratefully received.