By plane:
There are regular flights from Paris to Pau with Air France and also with Ryanair from London Stansted, Bristol or Brussels.
Transavia also fly direct to Pau from Amsterdam.

For more information, see
http://www.pau.aeroport.fr
http://www.ryanair.com
http://www.transavia.com

By rail:
Pau station is located near the town centre and there are regular direct trains from Paris to Pau which take approximately 5 hours.
For more information, see www.sncf.com

By road:
To check your itinerary, see www.viamichelin.fr / www.voila.fr / www.mappy.fr