Hi vinalspin
My thinking on the + £0.30p is some sort of one off charge on a per charge charging, like a standing charge on your gas and electric meters but I don’t know for sure and could be wrong. The way it’s written though does sort of suggest it’s a 30p per KWh on top of the KWh charge.
This particular charger is not located in an area where a user of the supermarket (if they did have electric cars) with little else in the area would use the charger because at most they would have only travelled a few miles to get there so they would charge from home so its a sort of catch a Monkey charger for the unsuspected who get caught out along way from home.
The nationwide company who run this charger are called “GeniePoint” so don’t know how they stand up with the competition as prices quoted above by Peter are a lot cheaper.