You have some options...
- Do it at the same time as you file your outbound flight plan
- Fill in a paper one at Le Touquet and hand it to the desk
- Use their free wifi to file via the net (Afpex, SkyDemon, Rocket Route)
- Call a BRIA and read it over the 'phone (Lille in this case)
I don't think there's an OLIVIA terminal at Le Touquet
HTH
Ian