We had our ASHP installed on 8th-9th April this year. So far we are getting an average COP of 3.25 overall; the combined value for space heating (effectively nothing since mid-late May), hot water and the standby consumption.
Breaking this down we are getting a COP of 3.68 during space heating and
a COP of 2.0 during the hot water cycle. Standby consumption is ~9W (really very low and probably lower than the elec our old boiler was probably consuming) which so far has represented 6% of the electricity consumed by our ASHP set-up.
The overall electricity consumed by the ASHP between 9th Apr to 9th Aug has been 382kWh, so the total running cost over that 1st 4months has been ~£70.
All these figures will change and consumption will go up significantly once the heating season starts again around late September (normally).