We have an XC40 hybrid and charge from a 3 pin plug overnight. It draws 10A. There’s no reason not to use an extension cable if the plugs and sockets are in good condition, although we don’t need to.. We have looked at all other option, commando plugs (16A) and charge points, but feel there’s no merit in spending the money. The car charges from empty in under 4 hours. Any alternative would only reduce that to 2.5 hours.