Fly/Drive/Train. Budget carriers fly to Pau and to Lourdes. The TGV line is Paris to Lourdes. Arriving by train has the bonus that the Station Hairpin is the second corner.
Circuit Usage / Configurations
1 - Startline
Lunch / Circuit Customs
I have only been there for the modern GP de Pau. Lunch and dinner was provided each day. The Saturday will have racing until late at night.
Street circuit racing - not easy to get to Monaco, so this is the next best thing. Be prepared for working on a live track with no run off. Short laps mean you have to be quick. Use of quick lift trolley jacks and cranes is common on most corners.
How to Marshal Here - Contacts
http://www.asac-bascobearnais.asso.fr choose "info club" then "pour officier sur une epreuve" (to officiate at an event)
or direct link to the form (in 2013) http://www.asac-bascobearnais.asso.fr/formulairePersonnalisable0001007b.php)
For the GP basic student hostel accomodation is available free of charge. 2 to a room. Quite far out from the circuit - car would be required. Plenty of hotels or B&Bs in town - standards of course vary. Public campsite just across the river - maybe 15 minute walk