"...Not ordinary people if they still depend on cars, cheap food and international supply chains - a situation that isn't showing any signs of changing...

We're all in that boat one way or another. Heating is a big issue in the UK...I use an all-round boiler stove that gives me radiating heat, hot water & central heating if required: At the moment it runs on small amounts of smokeless...it's direct and pretty efficient I reckon: certainly what I pay to run it is less than half what my neighbours pay for heating oil. When I put it in I made sure it could also burn logs or peat...without the coal lorry I would have to get wood delivered probably by tractor...of course according to the Scottish government reckoning, this places me somewhat near the antichrist and an enemy of the planet wheras in fact it probably extracts more direct heat energy per Co2 out of the nuggets than any power coal plant ever could by transforming them into steam then electricity then sending that across the grid to heat up some coils in a room. The cottage is over 150 years old...so just not suitable for a heat exchanger without ripping it apart and investing lots of dosh in huge amounts of insulation & eleven tripple glazed windows. The real evil is probably the 12 year old diesel car: but still giving 60 to the gallon and at a cost of £1,500 several years ago it's probably more CO2 efficient keeping it than buying a new electric. But unless you move into town cars are a necessity.

I have considered solar panels & battery, and reckon that would cost about £8000 + payback within ten years or so and also probably charge one small electric car from the supply which would do for life now...but I see there are problems with massive insurance costs for EV's ( because there's no real supply chain in parts yet & not a genuine repair network so if it takes a dunt it will probably be scrapped...) The Yanquis has slapped 100% duty on the small useful cheap Chinese ones too: I expect idiot Britland to follow...then of course, I wonder how the government is going to recoup all the revenue it will be losing from ICE fuel duty...will I end up paying penal fuel duty even though charging from my own solar supply? I could see that being a dumb government idea...
Foodwise we only have a small garden but it's packed with dwarf fruit trees...and gleaning the fields after the machines have past gives you a year's supply of spuds in a couple of days...and I make everything from scratch so a shopping trip every couple of weeks does us.

So yea...I reckon we are pretty efficient despite whatever legends the government would prefer to believe...because we have to be. We could be a lot more efficient co2 wise of course, but that would take some big investment money and given the uncertainties involved in trialing new technologies could yield some very uncertain returns.
We are of course in a lucky position because most people living in towns / flats couldn't even consider a lot this stuff anywise for various reasons: again age of housing stock being a huge deal... and if in rentals it's not even your property so forget it. Anywise when I see the cost & obstacles in the way for us in a priveledged situation to seriously do something I reckon most of the households in the UK will simply never get anywhere near any kind of efficiency.
The targets set are fantasy legislation, assistance available negligible or tied to officialdom and rip off recommended suppliers and the cheap import possibilities for EV's Solar panels,turbines...will I reckon be choked at source by political empire politics.

Sometimes I'm glad to be in my Sixties just to avoid what's coming...which reading the UK signs looks a lot like general atrophy partnered with the usual shortsightedness & scheming greed that's been our lot politically for the last fifty years.