Very close to what I posted
Veggies at Le Mans. Tricky. This is France - so you will not have much luck trying to find anything marked as "Veggie option" on the menu at resturants. Announcing you are vegetarian and asking what they have will normally result in the waiters throwing their hands up in the air, asking "you don't eat meat? how do you eat?" and
if you are lucky, a green salad for starter, followed by a green salad for main course (and they are NOT imaginative with green salads...)
If you go for one of the usual safe bets in the UK (curry and Chinese) you will find in France they have added extras such as bacon bits added which were not mentioned on the menu!
So,
eating out in France. What you can do... Pizza/Italian places are good. There are a couple in Le Mans which we go to almost every year. We were joined in an Italian Resturant Resturant one year by the (sadly now departed) Michele Alboretto, which was rather nice. We've gone back every year since - but no more (recognisable) drivers yet
Crepe's are also a reasonable place to be able to get Veggie fare without actually offending anyone by announcing you are veggie.
Asking for a dish "Sans (insert meat here)" and explaining you are
vegetarien will normally get you the dish you require, even if you do get a sad shake of the head from the waiter...
It IS worth saying you are veggie, as otherwise you are likely to get the thing turn up with some other meat instead - e.g. they think you just did not want the pork so they substituted beef!
Supermarkets. Don't bother looking for "vegetarian society approved" logos on food. There won't be any. British brands will have it removed if normally present. I don't think they want to lose French sales by indicating that there may not be any animal product in the item!
You will not find Quorn or Soya based meat substitute items. I'm sure we did once, but not for the last few years.
Cheese will not say if it has animal or vegetable rennet in it. So if you are really strict on that then cheese is out too!
You can usually find out the ingredients on items as many are multi-language. However some are not - learn French!
You can find pre-packed Salads in Auchan and Careffour (and Leclerc and Champion as well I guess, we don't go to them as much). These can be pretty good - with cheese and egg options. Also there are usually other pre-pack salad ingrediants that you can make a meal of.
Of course there is french bread. You can just fill up on a baguette and cream cheese. Rather good.
Portable bar-b-q's are plentiful in the supermarkets - if you can find anything to cook.
If you are bringing stuff with you, be aware how HOT it can be at that time of year. Food will NOT last, even with portable car-fridges.
At the circuit. There are resturants, but only one has a pizza, and you willl wonder why you are paying so much for a frozen pizza.
In the ACO Members enclosure you can sometimes find cheese pizzas as well. but not often (and you have to be a member, or a guest of one to get in).
Cheese baguettes are available, but often they are gone almost straight away. Of course no-one buys them as there is no meat in them So they sell out of the stock they have really quickly...
Hot items around the track are normally limited to Frites, and Chevre-chaud (a half baugette with melted goats cheese on it - rather nice. Sometimes this comes as a panini style thing).
So rather limited I'm afraid - you might end up on a bit of a cheese-fest, but it's only for a few days.