I am flying with Ryanair and have managed to print my outgoing boarding pass, but it says you can't print a return until 8 days before departure. What do you do then?
You print your boarding pass while at your destination. Make sure you don't forget, otherwise you'd be hit with a €55/£55 fine. Your hotel/hostel should be able to print it out for you. If not, visit the nearest internet cafe.
Also note that Ryanair rarely enforces their rule on non-EU passengers having to print and confirm their boarding pass, so you could also use a mobile boarding pass instead and most likely you'd be fine.