As the NIP was originally dated 19 September and this is over the 14 days can I ask for my case to be dealt with in the Magistrates' Court?
Regardless of the facts, or even if the "facts" are fiction, you can ask for the case to be dealt with in the Magistrates' Court, although that "option" is mostly psychological marketing - there is no need to actively request that the case be dealt with in the Magistrates' Court, if you are offered an out of court disposal, such as a COFP, and you do not accept it, it is then up to the police to instigate court proceedings.
To clarify, you are telling us that your partner is the RK of the vehicle in question, and that the alleged offence was on 26/09/2025 and that his NIP was variously dated 19/10/2025 (24 days after the date of offence) and 19/09/2025 (7 days before the date of offence).
You have also avoided telling us the nature of the alleged offence, or anything else that might indicate whether a NIP would be required.
Do I have a case?
The magic 8 ball says "Outlook not so good"
We are reliably informed that for an initial NIP to be issued outwith the 14 days requires a manual over-ride. We have been unreliably informed that in this case your partner is the RK.