I rent a car at £1
one way ...
Rent one-way from your city of departure and the airport of La Rochelle - île de Ré
.. which I use
during 24 hours...
You have 24 hours of rental with enough miles to make your move to the La Rochelle - île de Ré airport.
... And I leave
directly at the airport
As for a conventional rental, you drop the car directly to the La Rochelle - île de Ré airport parking.