i am thinking of buying some land in the south of france ,and would like to know if there is anything i need to know about leaving a caravan on the land for my occasional use until, or if i decide to move out there and build something permanent . will i need some sort of permission from the local mayor /authority ?
and will i have to pay the local habitation tax ? . i will be looking for somewhere fairly well off the beaten track . thank,s

so has no one else done this then ?
ps... does anyone have any good links to sites offering land for sale in france ?

look at www.notaires.fr
has links to every notaire in France, in English too. You can put in what you are looking for, price, size of land etc. Prices also include costs.
Other option is to just search for immobiliers in the area you are considering. Most of them have websites in English and list land (terrain) for sale.
You will need permission if you are looking to put a mobile home/caravan permanently on a site.