As others have said, there are things you need to do to organise the trip, and one reason ryanair is less expensive to travel with is that you, not them, do these bits and bobs.
However, I suggest as well as all the excellent advice above, you equip yourself mentally to expect a problem. I have flown with them many times and rarely is it simple. Do not become annoyed or upset if a piece of paperwork is awry, simply smile, ask for help and stump up any payment, as you are still likely to be getting a good price for the overall flight. And enjoy Limoges!