I would not want to use any Airlines loo's never mind their loo roll, I take my own but have never had to use it on any flight anywhere in the world.
Ryanair flights are so short, I dont see why anyone has the need to use the toilet in the first place and If you have a condition that means you use the toilet alot then I would think you would be use to having your own loo roll.
I always pack for anything I need from when I leave the house until I get to my destination.
Loo roll, wet wipes, Snickers bar and bottled water bought after security, is a must for any flight I take with any airline in any country.
Its all about planning ahead for any problem with any Airline.