"To state the obvious customs and police notification is (presumably) only required in respect of the in bound flight - no need to report you are going."
You have presumed wrongly as outbound and inbound notification is required for CTA and non-EU flights (from non-designated airfields), and you can already email the form to Customs. Unfortunately with 43 different police forces there's probably 43 different interpretations of the system - at least Customs have only got one place to send it.