You can't appeal a NIP, it's just a notice. All they are requiring at this stage is the name of the driver, which must be complied with (else a more serious offence is committed).
Once the driver is known the police will most likely offer a Conditional Offer of a Fixed Penalty (CoFP) or driver training course. At this point the driver can decide to take one of the offers, or ignore it and wait until a Single Justice Procedure Notice (SJPN) to be served.
The driver can then decide to either plead guilty to the SJPN, or not guilty. Pleading not guilty would then see the matter being referred to a magistrates court. Of course pleading not guilty would only be sensible if there was an actual defence, not sure what this would be based on the information provided.
