Yes, you do. We actually bought a printer in Calis it was £36.00 and printed off our boarding passes. We decided as we take a computer with us, a printer would be handy to leave over there.
However, you can download your boarding pass onto your phone and just show that at the airport.
Also, if you want a paper copy, I am sure you could ask an hotel or a restaurant that you are friends with to do it for you, or use an Internet Cafe.