I've got a large diesel engined car. 6 cylinder 3 litre BMW - lovely.The UK is leading the world in terms of renewable energy generation.
The infrastructure could not come within light years of coping with every vehicle going electric - the reliable generating capacity and distribution capability of the UK would have to roughly double - for that the protesters need to start by protesting for any form of renewable/green/non-polluting energy generation, and that would have to include nuclear (3? years ago the UK green energy generation dropped like a stone - there was too much cloud cover and too little wind).
There is no alternative to large diesel engines yet either - protest for more research money into that.
Human over popuation is the biggest threat to the planet's natural environment.