Re: hmmmm - sand battery
"As space heating costs in the UK are more than electric for the typical household,"
For now. Replacement gas combi boilers are being banned from 2035 or something like that. Everyone is going to have to go all electric eventually and certainly any new house built from about 5 years before the ban on sales of gas boilers, at least. At some stage, even people "hanging on" with gas boilers will either reach a stage of it being non-repairable and having to replace with electric, of eventually switch to local tanked/bottled gas as the gas network is under utilised to be uneconomic and turned off.