Right the rules:
If there was signs showing that speed detection was being used then he will have a ticket comming to you , as the gun will have recorded it.
However if there were no signs, (whether perminent or tempoary) then they should have had to follow you, because, the highway code stipulates that they need to make motorists aware of their presence, if there remiaing in a static position.
I hope this helps. If you do get a ticket, then you can do a couple of things,
Ask to see when the speed gun was last calibrated, if it wasnt calibrated within 24hours of catching you then you can prove that it is innaccurate.
2nd, if they had no signs to say they were there, (perm or temp) then you can contest it as, them trying to get motorists unfairly.
3rd (a bit late now) but come to a complete stop whilst they are trying to get your data, and it frazzles the speed guns. Only works on the hand held guns.
So I hope this was of some help to you.. I would suggest trying to find the rules in the Highway code, as you will need a copy of these if you get a ticket... to show the police.
As for points, you can be done for speeding once in your first 2 years, more than once and its goodbye licence, and then a 70min resit test which is not only harder than your initial test but also more pressure as it lasts twice as long
A