If your are flying from outside of Europe to the Loire Valley you will have to fly into Paris, to either Paris Charles de Gaulle (CDG) Airport or Paris Orly (ORY) Airport and then make your way by car or train to your final destination.

From the UK  (Stansted) and Ireland (Dublin) you can fly directly to the Loire Valley to Tours Airport. You can also fly with 'Low Cost' airlines from a number of smaller UK airports to Paris CDG, Orly and Beauvais plus some regional airports in France that can get you within driving distance.