Heat pumps when you don't have central heating

i live in a mid terraced fairly well insulated 3 bedroom house with NO central heating. only a gas fire for the main living room in the old Fireplace and an electric emersion heater for hot water. if it’s really cold outside we put on some portable electric heaters. i do have solar panels on the roof. is an air sourced heat pump a good idea, could it be switched over to act as air-conditioning in the hot summer, and how much would it all roughly cost.