Thanks everyone, I am really tempted to give it a go, it's just the thought of the washing that puts me off, though having said that I do so much that one more thing won't notice much ;D
How do you keep it still in the cage, I've discovered this week that Molly & Blossom will not pee upstairs at all (so far) so am wondering about fleecing their upper level for them & seeing how that goes before I decide about the lower level (they currently have hay on the lower level). I'm concerned it's going to slide about all over the place though.
Wish I'd thought about this when I was in Ikea last week as they have cheap fleeces!