I feel that some members are overdoing the "doom and gloom" a bit.
The proposed ban on new sales of petrol/diesel cars and light vans does not come into force for over 20 years, after which existing vehicles may still be used.
So about 30 years until the supply of good used ICE vehicles dries up.
In the interim I expect a gradual shift towards EVs, not a sudden mass adoption.
Charging an initially small, but steadily growing number of EVs need not present any great challenges.
Charging during the evening peak should be strongly discouraged by tariffs.
Charging overnight would be the norm. It seems unlikely that mass market EVs will have batteries greater than 45KWH, so charging overnight from a single phase 32 amp circuit is easily achieved.
" Smart chargers" that communicate with the grid are a distinct possibility. This would allow the charging demand to be controlled remotely so as to better balance supply and demand.
It would be a simple matter to provide three colour coded buttons on the charger.
RED=CHARGE AS QUICKLY AS POSSIBLE, at a premium price.
YELLOW=CHARGE MORE CHEAPLY subject to being fully charged by say 07-00 tomorrow.
GREEN= CHARGE VERY CHEAPLY INDEED, subject to be being done within 24 hours.
And while we are at it, similar controls could be fitted to some other appliances.
Some charging would probably be done at workplaces, but again should be remote controlled so as to balance supply and demand

Charging a million EVs all plugged in at about 09-00 would be a challenge. The same number with smart chargers that ensure that they are all done by 17-00 should be easy.
Presuming a million cars with 7KW/32 amp chargers, if they all charged at once on arrival at work, the total demand would be 7 million KW. 7GW for the first hour or two of the working day would be a significant increase in morning peak demand and require building a lot of expensive new capacity.
If instead the load was spread over an 8 hour day, then nothing would be added to the peak demand, and about 1 or 2 GW added to the average demand.

If instead the demand was spread over the working day