This will depend on how well your property is insulated. Most heat pumps produce low-grade heat so cannot produce high flow temperatures and therefore your property will not heat up quickly from cold. For this reason, they run most efficiently by maintaining the property at a constant temperature with heat emitters such as underfloor heating or fan-convectors designed for low flow temperature systems. Traditional radiators can be used however to work at low flow temperatures may require to be oversized.
For some older properties that are poorly insulated and where an air source heat pump alone may not cope at the coldest times of the year, they can be docked with a fossil fuel boiler to provide supplemental heat. Such systems allow the property owner to enjoy all the efficiencies and benefits of a heat pump whilst ensuring they remain warm all year.