No offence has been stated..it's guess work on my part. I did get a quick legal consultation and they said it probably is failure to submit my licence. But also confirmed that the law changed last August and it's no longer required.

I believe the system changed in Nov last year, so you are probably on the wrong side of it -

Yes it did, and it was the date of the offence which counted.

A call the office, profuse apologies, and sending off licence may well be enough in this case

I'm not so sure that it will. The last resort the police have is to prosecute through the courts. This is what they've done. A call offering to submit your licence will cost you nothing and is worth a try but I have an idea they will turn you down. To agree to your request they will have to defer the court action to give you a chance to submit your licence and I'm not so sure they will be prepared to do that.

There is some good news in that Magistrates have guidance which they can refer to in similar circumstances. It says this:

"Where a penalty notice could not be offered or taken up for reasons unconnected with the offence itself, such as administrative difficulties outside the control of the offender, the starting point should be a fine equivalent to the amount of the penalty and no order of costs should be imposed. The offender should not be disadvantaged by the unavailability of the penalty notice in these circumstances."

Of course this situation was within your control - in fact you caused it. But a kindly Single Justice may see fit to use that guidance and sentence you at the fixed penalty level. When you return your SJPN you should respectfully request that the guidance is considered.