I'm considering a replacement floor, mainly to get some insulation and a dpm
under my feet, but my query is about the layering.
I've got a picture forming in my mind like one of those geological
sedimentary layer diagrams.
It seems straightforward to have (from top down)

floor finish
screed
insulation
DPM
structural slab

But whereabout would one put the various services? i.e. soil, power, ch,
dhw, phone cables etc.

floor finish
screed
+ power, ch, dhw, mains water, cables etc.
insulation
DPM
structural slab
+ soil (as in 110mm stuff not earth)

And if there were UFH in the screed layer, should there be minimum
separation between that and cabling? I'm sure there's a convention, although
Chudley&Greeno don't shed any light, & not much in my building regs guide.

Toby.