Headlamp bean deflectors aren’t needed on my Santa Fe. Most Hyundais have a flat beam pattern that doesn’t need deflectors.
I drive quite a lot in France, usually a ski trip plus something in the warmer seasons. The speed enforcement cameras are fairly common near the channel ports, but less so farther away. There are more on the N roads than the toll paying autoroutes.
Fuel is a similar price to the U.K., with quite a premium on the autoroute service stations. I normally fill up at supermarkets in France. You can’t always get hot food at the services outside of mealtimes, it’s not a part of French culture to snack on the go. But there are usually sandwiches for sale. Some of the services near the tunnel have been closed to reduce the opportunity for illegal migrants to get into vehicles. So don’t plan on filling up with fuel near the tunnel.
I haven’t invested in a toll road payment transponder. I rely on my passenger to pay tolls. At the toll machines I use a credit card that has no transaction fees or commission when used abroad. Without that there would be quite a surcharge in some regions with frequent, low cost tolls.
I usually find French drivers very courteous, and it’s less tiring than covering a similar mileage in the U.K.
If I need somewhere to stay I often use the Accor hotels app, which gives access and easy booking for the brands they own.
Have a great trip!