Just to emphasise this:
There is no requirement whatsoever to enter the UK by a Customs or whatever aerodrome. You can fly into the UK and land in a friend's garden, no problem. Plane or helicopter, same rules!
All you have to do is inform Plod (the local police) and the UKBA (with a lat long if there's nothing else. I've had them waiting for me occasionally - very friendly (pretty easy gig for them I suspect).
Safe flights, Sam.