The quoted charge of 58p/KWh is also inaccurate I'm afraid, on a long journey (over the 320 miles range) I will normally want a break and will plan that around a charge point, if you use a charger on the motorway network you can expect more like 79p/KWh off the motorway network you can expect 29p/KWh but you'll get a slow charger with type 2 own cable, this will be no more than 22kw, but most EV'v only charge at 11kw on type 2. In this case your looking at 4 hours 20-80%.
In truth what you do is plan around Ionity stations and pay via Electroverse to get 8% off (71p/KWh) and put enough in to get to your destination.
From home to my second house is 405 miles so I drive to Gretna Green 251 miles arrive there with about 70 miles range (again using the 20-80% rule, dependant on many factors, but still always get there) and charge enough to do the remainder + a bit more to be safe that will be about 120 miles of range to add, about £30-35.00
That means the 405 miles cost me around £40.00 thats 10/mile ish
But remember on days like yesterday I charged to car from 31% to 80% completely free on
Solar.