Right, so here goes:
Cost to replace old gas boiler with new one in daughter's house =3k
Estimate to fit heat pump & parafanalia in our 3 bed electric only semi, more than 20k + upgrade to water pipes needed as pressure wasn't high enough & the inverter box would be sat in the middle of the back garden, as it couldn't be put anywhere convenient.
In the end I went for air conditioning heat pump at 7k and another 10k for solar & batteries.
It works better than the old storage heater & is significantly cheaper to run.
Ok I'm still heating water overnight on economy 7 and charging 8kwh of battery during the winter, but this month's electric is £80 all in.
If I went for the heat pumps they are trying to push, I wouldn't have been able to do solar too & I would have lost a pantry worth of space to the warm water cylinder.