That makes sense then.

How are heat pumps typically installed? Are they integrated into the radiator/hot water system? Or is some sort of forced air system setup installed?

I'd assume a mini split setup wouldn't be too uncommon. (Probably the cheapest route for most homes in the UK).

In the US the vast majority of homes and apartments are setup with forced air heating and cooling which really simplifies transition. I'd assume the UKs setup where everyone uses heated water to heat homes would make transition more expensive and costly.