It tells you.
You have to file a defence or Acknowledgement of Service by 29 June.
If you file an AoS you have until 13 July to file your defence.
Your defence would appear to be that the driver has not been identified and that the Notice to Keeper has been issued too late to transfer liability to the registered keeper. You are defending as the registered keeper, and you have not and will not identify the driver. You may want to post your draft defence here in advance of the deadline for comment and suggestions.
