Thoughts?
<mod hat on>
Firstly,
you are the one facing prosecution, a fine and points on your licence. Particularly when it comes to technical defences, the devil is often in the detail. If you can't be bothered to post an accurate and coherent account of what happened, why should those that you are seeking advice from bother to waster their time trying to help you? N.B. that is a rhetorical question.
The letter says you
need to pay £100...?
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Assuming that your account is otherwise correct, and that there was no accident or other issue that would negate the requirement for a NIP, whilst the requirement to serve a NIP is mandatory, the required details are merely directory - that is to say that if an error does not negate the purpose of the requirement to serve a NIP - to potentially enable you to identify and recall the incident that gave rise to the allegation while it is still relatively fresh in your mind, it would not void the NIP.
Whether or not the error invalidated the NIP would be for the court to decide.
Entering a hashed area bordered by broken white lines is not in itself an offence. The prosecution would need to show that thew circumstances were such that doing so on that occasion (or your driving in general on that occasion) constituted careless driving.