We can 'trickle-charge' EVs so as not to individually increase the instantaneous grid load, though of course 12 cars on trickle-charge will have an equal effect as 12 cars on fast charge even if they co-ordinate that to different times.I'm assuming that the government has scaled their assumption of electric car uptake. They must at least have an idea of the graduated increase of the demands on the grid.
HA-HA-HA Sorry, was that out loud?
As to adjusting our other electricity usage:
Heating. That's going to go up on average, as homes are switched from coal/oil/gas heating to electric, as mandated in the name of 'clean air'.
Cooking. Heating 'space' (oven, grill, hob) has changed little since the inception of the electric cooker - mostly by resistance conversion of electricity to heat - induction and infra-red heating exist and may be more efficient, and microwaving may be the most efficient but doesn't always give the same results.
Movement. Motors have changed little, there have already been efficiencies due to permanent magnets and other refinements, there's probably not much left to refine; recently British company has done what I've anticipated for many years, replace the permanent magnets with electromagnets, that will achieve weight reduction and reduce the expensive raw material requirement. But it's allegedly 'more complicated' in needing digital control. But fundamentally, no great saving available.
Light. Well we've gone in a couple of decades from mainly filament bulbs (great heat producers, aka energy wasters) to compact fluorescent, to COBB (LED). Great, they new use much less energy to produce the light, but the driver circuits still produce heat and consequently still fail, so still need replacement. If only the driver circuit could be moved centrally, and as a pop-out module, then cars and homes could be wired for COBB lighting without individual bulb failures. That would entail a doubling of cables as the return would need to go back to the driver, not vehicle earth or domestic neutral.
Washing, drying. see movement and heating.
Home entertainment. Basically see movement (speakers are just motors) and light (screens).
So there's little scope left to reduce domestic consumption, unless the procedures involving those energy conversions are refined. Smaller video screens could reduce their consumption (yeah everyone forfeit their 65" TVs for 14" - oh wait, why not go right down to 6"?), speakers in the ears instead of in the TV cabinet - yeah that's with us. Cooking, could be refined with smaller ovens, or compartment saucepans. Microwaving of ready meals, actually just moves preparation and cooking from the kitchen to a factory, and increases storage costs (chilled/frozen).
So, with an increasing population, it's unlikely that total energy consumption will reduce; the move away from consumer fuel usage means a heavier load on the grid in all things, not just personal transport.
Clive Sinclair realised, that personal transport that was only sufficient to carry a person, was the most efficient way to use electricity - why lug upwards of three extra seats around to move just one?
Of course that assumes the journey's purpose isn't to transport non-drivers and under-16s.
Ultimately, and it's long been a gripe of mine, commuting how it's currently done is waste of time and resources. Many people take on work that is far from where they live, however they travel it means an increase to the length of their working day (and usually not financially rewarded for, heck significantly penalised in most cases*), increase in stress, reduction of quality of life. And it's relatively a new concept - before motorways, railways, almost everyone worked close to home.
*take your hourly rate that you get paid for an eight-hour day, add two hours of travelling and then see if you're still receiving NMW.
Then subtract your fares/fuel&running costs/parking. Yep you're barely rewarded for your time at all - probably in work for three hours a day before you're in profit!