France probably has a tourist information office in your country; they have brochures about Corsica.
If you're interested in spending your holidays in once place, you should write to the local "Syndicat d'Initiative", that's the Tourist Information office. But don't expect these guys to speak English! Best thing is write in French, even if your letter sounds like a taiwanese operating manual... Ask your post office for the postal code.
This is the address of the Parc Naturel Régional de la Corse (PNRC);
they maintain most of the refuge huts:
Parc Naturel Régional de la Corse (PNRC)
B.P. 417
20184 Ajaccio Cedex
France - Corse