I have no specific advice to offer on leasing cars in France, but this comment made me wonder if leasing is necessarily the right option for you, young Volcano 
Car leases tend to have annual mileage limits, and the cost per mile for exceeding them can be high.
Yes you can get a lease with a higher mileage limit built in but then your monthly payments wil be greater.
(Obvs. high mileage affects the car’s future value).
Might be worth also looking at plain old hire purchase or a bank loan, especially on a “nearly new” vehicle that has done a good chunk of its depreciating already?
Just a thought.