If you plan to fly to here, a lot of connections to Biarritz and Bordeaux, and then 1h30 of easy driving through the foret.
Concerning people coming from UK, there is a Ryan Air connection from London, Dubin or Manchester to Biarritz. you can rent a car there. Also to Bordeaux airport from Cork and Edinburg.
Easyjet is also offering a wide range of connection from Bordeaux and Biarritz. Air France too, but more expensive.