Lunch is the big and least expensive meal: just be sure to dine between 12-2; don’t expect to be seated after 1:30 at the latest. In the South, stores close from 12-2, including bakeries (boulangerie). These shops have treats like mini Quiche Lorraines and ready made pizza slices. Large boulangeries have freshly made sandwiches and sometimes cold drinks for sale. Every village has public toilets and water fountains for hand washing. The fountains are ornamental so don’t refill your cantine there (eau non potable).
ALWAYS say Bonjour before speaking to a French person. You’ll get bonus points.
In a cafe a glass of wine or pastis is your cheapest drink. No need to tip other than small change. For a.m, order un cafe (expresso) or with a nugget of milk: une noisette, to save money. Capaccinos and “grande crème” are usually over 3€. You can take your time, no one is going to kick you out until they need the table at lunch time. Post Offices often have an ATM with slightly better exchange rates. Supermarkets take credit cards but because you don’t have a PIN you will have to sign.
Automatic gas service is country wide meaning that you’ll need to find a station with a cashier, a real gas station, or use your ATM debit card. The cashier can take a CC and you can sign at the booth. Buying gas is easiest on the autoroute, do not choose an AUTOMAT (24/7) if you want to pay cash.