If you estimate that it takes 5 minutes to fill a car with petrol or diesel, and 30 minutes to do the same for an electric car, which have half the range so need to 'refuel' twice as often, then changing the fleet from fossil fuel to electric might require on the order of ten times as many chargers as pumps. But then factor in that, say, half of the cars will recharge at home overnight, and maybe you need only four or five times as many.
It's do-able, especially as you don't need dedicated forecourts. Every car park, supermarket, hotel, restaurant, pub, public library, should install a modest bank of chargers. Planning law might be a useful lever here. And not to mention the on-street solutions in lamp posts, etc. What it needs is investment to ramp up the rate of installation, and also to increase the reliability so people can have confidence that their planned top up will actually be working when they arrive.