All the existing street chargers I've seen (there's a couple up the road from me) are like 1 or 2 here + there. Probably no more than 1 per thousand parking spot (might even be being generous there).
You'd have to install these chargers (which appear to require a fair bit of work to install) at every single parking spot in the UK to make it practical. Which is not really practical even if we had the money to do it...