Not counting the cost of, you know... buying a whole new car, of course.
That new car payment will be way, way more than you spend on petrol fuelling the vehicle you already have.
Of course, the petrol cost will rise, in no small thanks to that orange turd in America, but it won't approach the cost of a new car payment and the cost of the electricity on top of that.
That said, if you're going to go electric at some point, you may as well jump sooner than later to take advantage of those lower prices. There are a couple things you should be aware of however. One is that repair shops are harder to find (but are getting more common all the time). Similarly, charging stations aren't as common as petrol stations, but are also on the rise. The other is that an EV battery costs a lot more than a traditional car battery. You're going from a hundred pounds or more to tens of thousands — a significant portion of the total cost of the car! Batteries are consumable devices, and anyone who tells you otherwise is most likely someone who wants to sell you a new battery every few years. Though, this is changing too. The first EVs were practically designed to keep you paying perpetually. When you were done paying for the car, it was time to put a new battery in. That was the whole business model. For you to never stop making car payments. The batteries have gotten better. Research this yourself — you may come to the conclusion that I'm spreading FUD, or that I'm a stooge for the traditional car companies, or something like that. I'm not; rather, I just want you to go in having the right questions to ask.