Jake (and any others) - what about the sticks bound together and used on the gap in your wall (not sure what you'd call them?)
I've seen these used as roof canopies in Gran Alicant.
I presume the only problems are (a) getting the right size for the roof and (b) the fact that once you attach them, they're there for good (unless this unholy wind that everyone is talking about blows it away!!)
Just a thought (from a non-DIY person)
Peter