There are 2 sorts of system - an electric mat a bit like an electric blanket that is laid into the ceramic floor tile adhesive and water-based systems with pipes set into the concrete (on the ground floor) and under the wooden floor deck (on the first floor).
I take it you are thinking of the electric system because a water-based one for just a couple of rooms would work out costly (it needs various controls).
An electric one below the ceramic floor tile in a bathroom or other area with tiling works well. If you work on 200W per square metre it should provide enough heating in these rooms. It is controlled off a room thermostat, and obviously runs on peak electricity. I wouldn't put it into the bedroom, assuming you have conventional CH that you can extend with rads.