Suggest you look at Ryanair's web site

www.ryanair.com/en/terms-and-conditions#article6 requires an A4 sized sheet of paper.

See also the section about the Visa check desk which may apply to you. Also note the luggage rules.

If you can put up with an hour or so on a bus then Ryanair will be O.K. In 2011 I did two round trips with Ryanair and had no issues.