The initial poster asked about hours once on line. You can't and never will be able to put a precise figure on it so NEVER ever budget on a particular number of hours per annum. There are too many variables which invariably lead to an average of anywhere between 600 to 750 hours per year. Too many to go into I'm afraid, however a few guys on here have already touched on these.
Accept that firstly you, the SSTR, are a source of income for Ryanair. Get this around your head and then you will understand why you are flying anything between 600-750 hours per year instead of the regulated (and once the norm in FR) 900 hours.
This eats a load of people up (generally the ones who believe they will fly A). 900 hours, B). be based where they want to be and finally C) have a command in 4 years).
Unfortunately 'A' doesn't happen any more and probably never will for FOs. 'B' is down to luck if anything, however for many it will generally happen after a year or two; providing you keep your nose clean! C) with rostered hours dropping the years to the left seat are going to increase. O'Leary has already spoken about running the airline for cash and paying out the shareholders. It has to happen some time!