I for one would rejoice at seeing the end of diesels on the roads, although for trucks and buses there is not yet a viable alternative, so this needs addressing before any large-scale bans come into force.
I don't know why people talk about power station emissions when it comes to electric vehicles, and yet only consider tailpipe emissions from petrol and Diesel engines, as if the petrol springs up fully refined at the petrol station. Petrol and diesel need to be sucked out of the ground, brought ashore by boat, refined, distributed by tankers, and then pumped into the car. The refining process alone takes about 1kwh of electricity per litre.
I love petrol engines, just as I love steam engines, but they're a very inefficient method of providing power. The only saving grace that's given petrol and diesel a 100 year success story is the enormous amount of energy in the fuel, that means we can waste 80% of the energy and still get a reasonable range and running costs.
Regarding Hydrogen, you still need to get the hydrogen from somewhere. If you refine it from natural gas, you may as well just burn the gas anyway. If you use electrolysis of water to create hydrogen and then a fuel cell to convert it back, you'll get back about 40% of the energy you put in, compared to 85-90% with a lithium ion battery. This doesn't include distribution of the fuel either. We already have an electricity grid covering the whole country.
Regarding battery-electric cars increasing demand on the grid, we certainly do need to up our generation capacity in the U.K., although with vehicle-to-grid technology, an electric vehicle can be part of the solution as well as part of the problem. Electric vehicle batteries rarely stop working, they just suffer some loss of capacity, and once tue battery has reached the end of its life in a vehicle, they are designed to be used for grid storage, storing wind and solar energy when it's available and putting it out when it's most needed.
