MummyTummy - foil can be an effective deterrent. We got a new rug which our two indoor cats took a liking to and were sharpening their claws on. I ended up putting massive strips of foil all over it - the first time one of them stepped on it was hilarious, he jumped about a metre in the air! We did combine the foil with the spray bottle though, as well as making sure we had a scratching post nearby (that's not your issue though).

I would say try the foil and actually put it around the top of the cot, so that when the cat tries to jump it, it connects with the foil.

When we have kids I think we'll try the netting over the cot idea.