We holiday regularly in Capestang and have eaten at the Grille many times, most recently last week. AS the name suggests, grilled food is the mainstay of the menu sausage, lamp, beef, duck all cooked to order and served with a mound of frites for between 10 and 15 Euro. They also do a good (i.e. thin) wood fired pizzas and a selection of (enormous) salads as well as the plat du jour menu which is fantastic value at around 11 Euro for three courses.
I have read other reviews which suggest that the English are not welcome at the Grille but that has certainly not been our experience; even though we are perfectly happy to order in French the staff typically speak English to us from the get go (to the point that I had to ask them not to so that we could practice our French) and they have without exception been very welcoming, courteous and prompt. They are even happy for us to stay at our table for half the afternoon using the free WiFi long after lunch service has finished.