I remembered your estimate Kezo and based on the calcs this guy comes up with I think you were bang on. I agree the heat loss is very important, especially with a stand-alone ASHP but less so in my case. If an 8kwh pump can cover me for 90% of my heating and the combi for the other 10% I’ll be happy with that.
The only person who got all his work done by Friday was Robinson Crusoe.
Anything i post over three lines long please assume it is an article lol.