As I understand it, as far as customs/immigration is concerned, there is no reason why you cannot roll up at Exeter from abroad anytime the place is open as long as you have filled in GAR form and given the appropriate amount of warning dependant on where you have come from. I do that at my private strip, I don't see why an airport should be different.
All the customs hours stuff applies (in the UK) if you arrive unannounced and/or (?) if you are commercial/scheduled with lots of pax.
Last edited by Romeo Tango; 29th Aug 2018 at 10:16.