Sigh........drives me mad when people speculate and believe the utter rubbish others say based on nothing more than their own or others obtuse opinion.
If you want to know the definitive position......
Look up the Sentencing Guidelines for summery only offences.
https://www.sentencingcouncil.org.uk/offences/magistrates-court/item/speeding-revised-2017/
A fixed penalty notice is a NOT a conviction, it is an offer to discharge your liability from prosecution by paying a fixed penalty. You have the choice to go to court and be prosecuted OR pay the fixed penalty.
On a UK motor way the limit is 70 (for car PLG) if your recorded speed is under 90 you will not be disqualified.
If your defender is classed as an LGV this would be an aggravating factor, although in itself not enough to elevate the starting point to the next band.
PS the Police have nothing whatsoever to do with setting the camera trigger limits, this is done by the local Safer Camera Partnership, it is 2MPH above the limit as a minimum.
Calibration arguments will not work as each camera self calibrates and provides secondary report for each offence, this calibration is then verified by a site visit at set frequencies, whereupon a sec 9 standard statement to that effect is provided.