I don’t know exactly how Motability work sorry but, this drilling one hole in nonsense as the price of a SDS bit is included in a job. If I charged per hole I’d would have never got any work!
Having said that I believe Motability to be somewhat lenient, if you neede and extra hole or meter of cable!
Is your consumer unit on a outside wall and where is it in you house in relation to where you want your charger?