Pau airport is approximately 1 hrs drive away, which is served with regular flights from the UK with Ryanair and Air France
Toulouse, which is less than 2 hours drive, has flights from various airports in the UK with Easyjet and British Airways (whose prices can be surprisingly good).
Lourdes, which is 50 mins away and has flights from a few UK airports, including Stanstead London.
is available at both airports from Avis,
Autos and Easycar
St. Malo is the most direct and closet Northern France port to the Gers,
with sailings from Portsmouth with Brittany
Ferries, leaving a car journey of some 8-9 hours. Alternatively,
take the ferry to Santander with Brittany
Ferries, or Bilbao with P&O
Ferries, and drive up from Northern Spain, a journey of 5 -6 hours.