The procedure is the same whoever is driving. The registered keeper of the vehicle will be sent a Notice of Intended Prosecution (NIP), detailing the offence. Plus, a document called a Section 172 notice. Whether you agree with the NIP or not, within 28 days you must complete the Section 172 notice declaring who was driving the car at the time of the offence.
The driver will then receive either an option to attend a speed awareness course if they have not been convicted of any other speeding offences in the past three years and have been caught driving over 10% plus 2mph of the limit, but below 10% plus 9mph. In a 30mph zone, this means anything between 35mph and 42mph, while in a 70mph zone it means anything between 79mph and 86mph. (These figures are only guidelines and different police forces may set different limits.)