Right, all of the above is great advice in terms of speed limits applying to LGVs and all those other complications; but as regards punishment/points/disqualifications etc. you might be at a stickier wicket...
Basically, if you've got an NIP and you plead guilty by reply (ie don't go to court), you're going to get three points added to your licence; a few days later, you'll have a letter from those lovely folks down the road from me who will advise you in another five days you're licence will become invalid and you'll not be alllowed to drive. As you're aware, this is a revocation under the New Drivers Act; and as such, no courts are involved. As soon as the fixed-penalty office advise the DVLA of your punishment, they will act to revoke the licence under the terms of the New Drivers Act.
If you wish to avoid a revocation, you will HAVE to go to court. If it's confirmed, and you actually should have been doing 60 or something (as opposed to the standard 70), when you go to court you should explain clearly (and humbly) that you're not there to make excuses or deny what you did. Explain that while you were unaware that you were so much over the limit for your type of vehicle, you realise that it was your responsibility to know, and therefore you understand you were in the wrong; as such you will gracefully accept your punishment, but you would request that the court consider a fitting-punishment that doesn't affect your ability to drive; as your job and family depend on that...
Now here's the important part... 73 in a 70 (even if it should've been 60 for your vehicle) would probably be a 'three points and £60' affair - by going to court you risk this being increased; HOWEVER, if you put a suit on, make sure you look tidy when you turn up, and stick to the paragraph above, you'll probably be OK... THE ONE THING YOU WILL HAVE TO INCLUDE THOUGH IS AN EXPLANATION THAT YOU ARE CONCERNED ABOUT THREE OR MORE POINTS CAUSING A REVOCATION DUE TO 'TOTTING-UP' AND THE NEW DRIVERS ACT...
I would guess if you stick to all that you'll either get a) a fine on its own, or b) a fine and two points.
The reason why I stress that bit about totting-up and the New Drivers Act is becaue I've been bitten by it...
One night a while ago I was travelling from Bolton down to South Wales, and after using A-roads to dodge standing traffic on the M6 which ran pretty much from Manchester to Birmingham (due to numerous road-works and accidents etc.); I picked up the M5 in Birmingham. The road was pretty clear and due to the massive delays I'd had already, my heart ruled my head and I squeezed the loud-pedal somewhat harder than I should've. I ended up zipping past an unmarked Volvo at 105.54mph. Obviously I went to court...
I tidied myself up, and humbly explained that I wasn't making excuses, and asked for a fitting punishment that wouldn't affect my new job etc. - I even added that I'd learned my lesson each time I got in the car in the four months between being stopped and going to court, I was reminded every time I sat behind the wheel. At that point the magistrate said that she could see I was clearly remorseful, had learned my lesson, and would not therefore disqualify me from driving. I got 6 points and a total of £375 in fine and costs...
The one thing I didn't know though (and I've definitely learned my stuff now!), was that the points would be applied four months earlier, on the date of the offence (and not the date of the court case). The date of the offence was 23 days inside my probationary two years; and yes, a few days later the DVLA wrote to me to basically say it didn't matter what the court's intentions were, they were having my licence back. I enquired about appealing with the DVLA - there is no chance, the only option you have is with the court. A solicitor told me that if I appealed to the court, they
may adjust my sentence (
read: points) because their intention was for me to keep my licence, but that process would take longer than just getting a new provisional and taking my test again... So that was my only choice, I had to do both tests again - and I've still got the six points on my licence (although 'totting-up' counts from your FIRST test-pass, so thankfully I'm not in the situation where I've got two years where I can't get a single point)...
So the moral of the story, make sure the court considers the New Drivers Act before they pass sentence if you do take it to court (which I think you're going to have to if you want to avoid automatic revocation)...
And finally, if you haven't returned the NIP yet, go through the NIP wizard at
http://www.pepipoo.com/ - it might be able to help...
Good luck and best regards,
Rob.