I've fixed and varnished the painting today. I'm pleased with the effect. Its certainly a different way of presenting a painting.
I hung it on our wall so you could see the effect. I used satin varnish to give the painting that slight sheen and to bring out the texture of the watercolour paper. Ideally I would put the painting in a floater frame for a bit more protection but I will have to get one cut to size as I didnt have one that would fit to hand.
Stretching the paper over canvas stretcher bars is certainly a technique I am going to continue to explore.