This might be some help, a French carb counter with some restaurant carb counts in it.
http://chretiens.republicains.perso.neuf.fr/politique/sante/medtronic_aliments_&_glucides.pdf
If you really want to low carb there are lots of large main course salads with very few carbs, you can normally get a steak with haricots vert (green beans) rather than frites, there are lots of dishes that don't actually have lots of carbs , so for eample a plateau de fruits de mer(shellfish) or some moules mariniere (mussels in white wine) have almost none (though moules normally come with frites and mayo) .
If you want to eat al fresco, there are many traiteurs where you can buy cooked meats, fresh rotisseried chickens and
pâté with various veg in vinaigrette dishes (plus of course cheeses but not always in the same shop) .
There are lots of salad veggies available.
Because, I'm not a low carber I would have bread with those but I go for artisan made nut breads, pain aux noix(walnuts) or pain aux amandes (almonds) or pain aux seigle (rye) You may also find pain aux lin (ie with linseed but that will be a mix of linseed and ordinary wholegrain or multigrain flour as are the others.) Typical 'French' baguette is very high GI (though is very light so not a huge number of carbs in each chunk)
Desserts tend to be small and very rich so not nearly so sweet or so high carb as desserts in English restaurants. Even some fastish food restaurants will serve fruit but berries tend to have had sugar added.
If you aren't in an 'international' hotel then breakfasts may be your biggest problem, even as a non low carber I take my own oatmeal and fruit with me when possible. There are apparently bars that will serve you hard boiled eggs in the morning, I've never noticed one.
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