If he's been told that he is getting the summons then that will mean that the officer will put his statement in regarding the incident including all relevant information such as speed, visual evidence, speedo calibration and number then submit to the CPS for their decision. The summons will then be sent out including a time and date for the court appearance.
However a NIP will have to be issued within 2 weeks to inform that he is being considered for the prosecution of 'offence' if he has not already been given that verbally by the officer at the time, that is the law.