Fines in France for not having driving licence

We're driving to the French Alps next week and due to the DVLA not
being able to return my partner's driving licence in time due to an
address change, she won't be able to take it with her.

I hear if you can't produce your licence if required you're fined on
the spot - anyone know how much?

I really don't want to have to drive it all myself and of all the
thousands of miles I've driven thru France I've never needed mine but
want to weigh up whether it's worth risking it.

cheers