We simply don't have the generating capacity in the grid for a switch to EV, not now and not by 2040 without some rapid decision making, changes to how procurement is made and without significant investment. The whole power generation state of affairs is a shambles, not helped by dithering successive governments refusing to commit to more nuclear power. A few years back before I started my own business, I was interviewed for and subsequently was offered the job as a project manager for the civils decommissioning aspect of two power stations. The interview was in multiple parts as they whittled 200 candidates down and the latter stages involved meetings with various parties employed by different organisations who were meant to be working together. It was a political farce, and one party was distrustful of the other with poor efficiencies for the schemes as a whole. I was appalled that something so important had been set up and run so badly so I refused to take the job (and am ever thankful for that decision).
Until the government gets its act together and our major grid infrastructure procurement is free from some of the EU shackles currently making decisions on best contract practice too inflexible, we won't meet demand any time soon, unless with over-priced foreign investment and lack of long term control of grid management and profits.
Until then, I see our best bet as solid state battery hybrid technology using smaller, more efficient petrol engines and solid state batteries. This technology is being heavily invested in by a few of the major players at present, including Ford, who were to release their first hybrid examples using I think 1.2 triple cylinder engines sometime during 2018/2019.
https://gas2.org/2017/03/04/solid-state-battery-may-next-great-leap-forward-technology/
https://cleantechnica.com/2018/01/30/ford-chief-plans-post-lithium-ion-world-touts-hybrids-autonomous-vehicles/