Piperboy, entry to Europe is a non event.
A few weeks back I landed at Le Harve for fuel en route to Spain (having PPR'd and Flight planned there) and whilst doing so couple of chaps casually asked to see my passport and then was on my way again.
On the way back it was even easier, I departed Abbeville, a non customs airport and landed at Bentwaters, again non customs, just by filing a GAR online.
Just file a VFR flight plan any time you cross into or out of France and its easy peasy.
Regards
UA