[marsokod]

I have a heat pump in such a house, even worse actually since it is a semi-detached. I did not need to do any extra work, and it works fine. My savings are not great, but that is also mostly because I don't have a hot water tank so I still need gas for my hot water. We just replaced 3 radiators, one of which is actually still permanently shut and I am still doubtful about the need for the other twos.

For the walls, it can become quite expensive to insulate it. But at least for the wooden floor, you have a cheap option: lay a new laminate flooring with proper underlay. It will cost typically less than £1000, you'll avoid damaging your wooden flooring, and also improve the thermal confort by removing the air leaks and insulating more.