I live in west London not in Essex I only visit Thurrock services on route to my children.
There are big enough EV’s out there just none that would ever make it only the scheme due to the price and bhp caps.
If you mostly do short trips on your own or as a couple and don’t need to bring large scooters or have a large hoist fitted it may be fine.
Ev ownership isn’t for me yet, maybe in 10 or 20 years every model will have EV versions and charging them will be just as common as petrol stations are now.