In practice, it is usually fairly straightforward to take a Ryanair flight to one destination, and then travel on to another. I have done it many times and have been lucky enough not to have had any delays or problems. Some groundrules, though:
- As always with Ryanair, try to travel with just hand baggge;
- Check in online (you have to now anyway);
- Leave plenty of time to get landside at your intermediate airport, then back through security, especially at Dublin and Stansted;
- Be prepared with a Plan B you can afford should you miss a connection; and
- Only use this way of flying if your journey is flexible. Fine if you're travelling alone.
That said, I have successfully changed planes and airlines - including Ryanair, easyJet, flybe, Jet2.com, WizzAir, SkyEurope, Aer Lingus and Aer Arann - using this method at BFS, DUB, GRO, PRG, BCN, STN, SOU, GVA and BRS. Most were easy; the longest walks and security queues are generally at DUB and STN. I wouldn't, however, recommend this method for going to important or time-critical events; though it's fine for coming back from them.