The following is simply to make you aware of the priorité à droite rule in France. It should not be regarded as a legal definition of the priorité à droite rule.
In France, unless signs indicate otherwise, traffic joining your road from the right has priority. If in doubt, give way.
You will, of course, be cycling on the right hand side of the road.
In practice, the rule applies in built-up areas where you must give way to traffic coming from the right. However, the advice is to exercise caution at all times wherever you are.
Outside built-up areas all main roads of any importance have right of way. This is usually indicated by a road sign showing a yellow diamond within a white diamond.
Our cycling will be largely on small country roads, passing through many hamlets and villages so you may rarely see these signs. In fact, if you see such a sign with a diagonal black line through it, then this indicates that you do not have priority.
Therefore, you should always exercise caution whenever you see traffic joining from the right.