I should think that St Martin qualifies as the most westerly place that is politically an integral part of "Europe". They officially use the Euro and vote in French and EU elections. It is part of the "Region" and "Department" called Guadeloupe. Admittedly a DOM, not within the hexagon.
This would make the Grand Case Airport TFFG the most-westerly "European" airport. Second would be Baillif Airport at Basse Terre on Guadeloupe itself. Google Earth grossly mislocates Baillif. It is in the northern suburbs of the town of Basse Terre.
Pardon this niggling response.