OP reporting back ( belately... ) :

I had made a very long list of the restaurants you all recommended.
I could of course only try a few on the list due to time constraints and in the case of some of the restaurants, I didn't like the week's/day's fixed menu.

But I am going back in August so I'll try more of the restaurants then.

I ate at :
Les Bouquinistes - very fancy looking food and tasty as well.
I had the 3 course lunch deal. A very nice experience.

I had mackerel in a sort of soup for starter (tasted very fishy, which
is fine by me), white fish (?) on
vegetables for main, and a sort of citrus symphonie for dessert -
sorbet, mousse and cake, very well presented.

Les Cocottes - My favorite of the restaurants visited.
Had their two course lunch deal (some fantastic well-cooked beef).
Due to the serving in cocottes, the food is really hot which I like.
I ended up eating there twice, partly because I went to eat lunch at
Le Voilon but didn't fancy that day's lunch menu (the restaurants are
almost next to each other) and partly because I really liked the food.

I cannot remember my starter very well - it was vegetarian, some
sort of rice balls. The main was paleron bæuf braise on pasta shells
with red wine sauce -
the meat was extremely tender and had a good strong taste.
Second time I only had a main dish - shellfish linguine.

Cafe Constant - also very nice food. Good choices on the
menu card.
Very crowded though.
I had a salad with artichoke hearts for starters and joues de bæuf
with fettuccine for mains - again the meat was very tender.

Le Grand Bistro - Had the all inclusive dinner option.
Plenty of choices on the menu card which is important for me as I am
a bit of a picky eater.
Food was not very fancy, more like traditional food but I found the
quality to be perfectly fine.
And my son liked that they happily served him the welcome drink
and wine without asking his age.

I had smoked whiskey scottish salmon - nice quality, beef fillet
with pommes frittes, and some sort of chocolate cake with icecream.

I tried eating/drinking at L'Avant Comptoir but it was sooo busy I couldn't even get a foot in.

I am looking forward to trying some of the other recommended restaurants in August ( those that'll be open.......) and a revisit to Le Cocottes.