Is it a customs airfield?
Yes, of course, otherwise one could not go there to/from the UK.
It is Customs PNR. I don't know how much notice they need.
Customs email bse-cherbourg [ a t ] douane.finances.gouv.fr
Cherbourg is also popular with people who want to go to e.g. Jersey but forgot to file the Special Plod GAR 12hrs ahead
