Do you speak French? How is your written French? (there are forms to fill in). Do you want to breed (you don't really have enough land) or just buy in stock lambs? Either way, you legally have to register (numèro de cheptel). There will be a fee to pay, plus you will be invoiced each year (amount varies).
What area are you in (e.g. Brittany)? This website is good, the French isn't too difficult to follow but depending where you live, you may be in a different area when applying for your numèro de cheptel :
http://agriculture.gouv.fr/identification-et-tracabilite Will say at this point; only buy from sellers with a holding number - sheep should have a tag in each ear, one of which
must be electronic. Get the movement papers correctly filled in when you collect. But before all that make sure you have good fencing and are ready to take them.
Buy a basic first aid kit, plus wormer and Butox and some foot paring shears. And some violet spray. Your vet will have most of these items, the rest you will find in places like Agrial.
You will have to have your sheep blood tested each year for Brucc. And register your flock with your vet - both of you fill in the form (and the vet will stamp it) which you will receive from the governing body confirming him as your designated vet.
Is that enough to get you going!? Any more info needed, just ask.