As said there is normally a unit which combines all
with a old boiler, but with a heat pump the water temperatures are normally lower, needing pipes with a larger bore, and standard radiators would be far too large to use with the lower temperatures, so often looking at fan assisted radiators, and the building management system to run these is rather expensive.
But since the heat pump compared with a gas or oil boiler is often a lot smaller output, the idea of allowing the home to cool overnight or when not occupied does not really work, the recovery time is too long, so the heating is not turned off.
Also all pipes need lagging and fan assisted radiators need scavenger pumps to remove the condensate in summer, and clearly UFH can only heat, only the fan assisted radiators can cool as well.
I have only used heat pumps when living abroad, Algeria and Hong Kong, and in the main stand alone units in each room. Electric is far more expensive to gas or oil, but in the main heat pumps were used to cool rather than heat, and although some would reverse the pump to swap from cool to heat, many had simple elements for the heating, just as well as they could easy freeze up even in the Sharia so have a heater to defrost was a good idea.
The larger units were installed by heating and ventilation engineers, and engineers want good pay after going to University to get the qualifications, and it is not really a job for an electrician or plumber. The system needs to be designed, the this is how we always did it does not work, it needs skills well above what I have, I only have a very basic degree.
