My understanding of this announcement is not for any current £40Bn deficit, although Covid is causing a hiccup in revenue of £2.5Bn per lockdown month, but the £40Bn is in reference to everyone changing to electric that will reduce the duty collected at the petrol and diesel forecourt pumps.
I don’t think we will see toll station popping up on every street corner but more than likely it will be some sort of GPS tamper proof box built into every electric car sometime in the future.
I’ve said it before and will say it again for all those who are lucky to have found a suitable EV on Motability now to make the most of the cheap motoring as my guess is, that will be gone by the end of this decade.?