Bring your shopping bags to avoid paying for carrier bags.
A lot of OTC medical type stuff is only available in pharmacies in France when it would be in supermarkets in the UK, and it can sometimes be difficult to find an exact equivalent. So I would bring a small selection of whatever medicines you most often use at home as well as your normal first aid kit.
Bring scissors (gîte will probably have them but useful on days out) to open packages.
Pens and paper for games, and for shopping lists and any general notes.
Personally, I wouldn't bother bringing the small things like herbs and spice, dishwasher tablets etc. I would wait to see what's supplied then buy what you need and be prepared to take the leftovers home at the end of the holiday.
It sounds obvious, but don't forget a sufficient supply of plug adapters. If you have to buy new, I prefer the ones with USB ports and two or three plug sockets for one adapter, then you can plug in 5 devices on one socket.
A tip that people in Toulouse (and the Southwest in general) can get touchy about the term 'pain au chocolat', although mostly in a light-hearted way. The word they use is 'chocolatine'.
If you've left applying for the Crit'Air sticker for the last minute, you can print out and display the online confirmation for use until the proper sticker is delivered.