The police have you by the b*lls. They can take as long as they like to send you the letter, as they will claim that the registered keeper record they had was out of date, and it has taken until now to find you.
As far as speeding up to avoid an accident, they will say if you were overtaking somebody who was already speeding, and suddenly braked and veered across to your lane upon seeing the camera, then clearly you must have already been speeding before you sped up to avoid him.
They will have you either way. Even the courts are biassed against you, so dont count on a fair hearing by a judge.
They aren't even interested in it being a money making set up. Many of them are, but you will never win that arguement.
I got a �570 fine and 6 points in a case where they could not even proove I was speeding. There were loads of inconsistancies in their evedence, and the whole case was based in interpritation rather than hard fact, but I still got stuffed.
Swallow your pride, and pay up. Three points and a �30 or �60 fine isnt the end of the world, and the points are dropped after 3 years.