Frustratingly he tried to deal with things himself, but I have managed to gather what I can from his NOIP letters. What is interesting about this is that you either pay or plead your case in a court.
So let's fill in the gaps..
1/ He got a NIP - details, location and dates of event and paperwork would help.
2/ It seemed he replied naming the driver as he now appears to have a Conditional Offer of a Fixed Penalty?
3/ for 43 in a 30 that is not really 'interesting' it's perfectly normal, too fast for a course.
4/ Absent an identified defence the fixed penalty (and if he accepts it make sure he reads the instructions for sending off the licence details carefully - and complies!) is all but certain to be the cheapest and least painful option, financially and that it would be 3 points, in court 4 or 5.
5/ That may take him half way to licence revocation, it's the point of the legislation, so perhaps take the time to identify with him why he was speeding so he can learn and not do it again, most common causes for speeding are not a conscious decision but a careless one.
Common reasons for speeding we see on the forums - hope this helps.
1/ Not understanding how limits are signed particularly for restricted roads (system of street lighting every 183m/200 yards or less) where the street lights are the 'sign' for the driver it's a 30 limit. Unless repeater signs indicate a higher limit applies.
2/ Thinking dual carriageways are 40 'just because' they are dual carriageways so not a 30 'surely'.
3/ Not actually paying attention to limit signs but 'it didn't feel like I was speeding'.