I would be inclined to write back to the police - and copy in the court, and the speed awareness people explaining the circumstances - just brief bullet points with dates, so they can see what has happened.
Add in a grovvelling apology, and confirm that it was never his intention to waste anyone's time, and he hopes that the police will accept his apology on this occasion, as he completely understands the seriousness of the situation.
Hopefully that will head off the court action.
If not, write to the speed awareness people again and enclose copies of his letter to them and to the court and police, and ask if they could allow him to attend the SA course.
ideally, he will get off the court appearence, be able to attend the SA course, and have no more points and no fine.
Worst case is that he cannot attend the course, he gets the points and a fine, and also a fine for wasting police time.
Best of luck.