I know we are getting off subject now, although it has some relevance in touching on the availability of electrical capacity to charge up car batteries, but the whole idea of pumping hot water around a house seems a little daft to me these days. I have a couple of portable oil filled radiators which I use to boost the heating in the coldest parts of the house on the coldest days. I have seriously considered installing heating based on these given they can be individually controlled by timers and thermostats and controlled by any home automation system to provide truly agile, focussed heating where needed.
Can the heat pump just be used to generate local electrical power, perhaps supplemented by solar and subtle wind turbines to create truly local power into the grid, rather than converting each property, if indeed that is even possible? In my home town there is a huge empty gasworks site, situated by a regularly fast flowing river, which could probably be repurposed, especially given it is already a brownfield site.