Under-floor heating and sub-floor

I want to replace my existing carpeted living room with a wooden/laminate floor – as part of this project, I was also considering putting under-floor heating in.

Currently, the floor consist of carpet, underlay (8mm), T&G chipboard (18mm), polystyrene (45mm) which all sits on a concrete floor, which is part of the building structure (I live in a top floor flat).

So, I can either throw away the existing layers and start from scratch, or I can keep everything and just lay the new wooden floor over the underlay, but I’m worried that this won’t be stiff enough for wooden floor, and it might flex.

Bearing in mind that the existing distance between the structural floor and the carpet is about 75mm, what options do I have if I want to install under-floor heating?

I’m not really sure what my options are for putting in under-floor heating, I was thinking that if it was something I could hook up to my existing central heating system, then it could be controlled with the existing thermostat, but maybe an electric one would be more efficient?

My initial guess (uneducated) is that I would keep the chipboard, and screed over it (and maybe the heating element) then put a thin layer of underlay, then put the wooden floor on top of this.