Indeed, most French eat bread and butter with jam for breakfast. Depending on where you're staying you may also be offered soft boiled eggs and/or yoghurt. You may also get a selection of meat and cheese to put on your bread, in which case you can eat the meat, sans. Ordering at restaurants is easier, plenty of fish, meat, veggies, real butter, etc . . . If you don't want to offend tell them you're gluten intolerant and ask if you could just have a soft cooked egg and perhaps some ham. Most places will be fairly accommodating.