Thanks for updating the image.
They totally ignore your appeal point, don’t they?
The notice needed to be dated 13 April or earlier to be deemed served within 14 days.
A simple IAS appeal will cost them £23 and should be that the driver has not been identified and that with the claimed breach of terms on 1 April, the Notice to Keeper was issued too late to use the provisions of PoFA 2012 to transfer liability from the driver to the registered keeper.
I wouldn’t suggest adding other points, because then they will ignore the difficult points. It is true that “leaving the site” is also pretty unenforceable, but the issue date is a much clearer appeal point.