I guess I ought to declare an interest. I was a magistrate for 20 years until 2008, during which time I sat on 20,000 or so cases, half of which were in the motoring court dealing with the full range of motoring offences. Where speeding offence arose, in part, it seemed to be that many motorists see speed limits not as 'limits' but as 'targets'. Where accidents occur, it's usually not just due to speed, but not driving in accordance with the conditions of the road, driving too close to the vehicle in front, general poor observations and distractions - fiddling with the radio, sat-nav, on the phone, kids/dog in the car etc.
Time and again I heard the same comments in mitigation - 'not a deliberate intent to flout the law', 'my speed drifted up in a moment in inattentiveness', there was no traffic, I drive hundreds of miles a week and this is my first offence in thirty years, and so on.
You usually only end up in court for speeding if you're doing more that 30 in a 20 limit, 40 in a 30 limit, 55 in a 40, 90 in a 70 limit. Below that, its a fixed penalty of 3 point and a fine, (unless you already have nine points and stand to be disqualified). If you exceed the above limits, (EG 41 - 50 or above in a 30 limit), you're off to court and looking at 6 points or 7 - 28 days disqualification plus a hefty fine. At those limits it's not down to inattentiveness or bad luck, but bad driving, and a bad attitude to road safety.
Really, if you're doing anything in a car which - if you did it on your driving test would cause you to fail - you'd best not do it. As to speed awareness courses, to an extent, whether or not you are offered one can be a tad random as it depends on whether there are places. The courses aren't punitive or demeaning, are well run, and the chances are that you won't offend again.
The Magistrate Sentencing Guidelines for the whole range of offences aren't secret - you can view them at his link, which explains how magistrates consider the mitigating and aggravating factors of both the offence and offender:
Magistrates’ courts sentencing guidelines – Sentencing
Despite what Daily Mail Readers might think, 'a slap on the wrist' isn't listed, nor a 'got-off-with' ('got off with a fine', 'got off with probation,'), and a 'suspended sentence' does not mean hanging, which ended in 1965.
When I was approaching 80, I decided to take a mature driver's assessment with the Institute of Advanced Motorists. I went on to take the course, culminating in the Advance Driving Test conducted by a serving police officer examiner, which I was rather chuffed to pass. I can truly recommend it. My main fault was that having spent so many years as a magistrate, subconscious paranoia of ending up in court had caused me to drive like a funeral director. Driving is much more enjoyable now, and I never get impatient when in traffic, because I AM traffic!