I'm in exactly the same boat, time to get a canvas (or laminated shade cloth) awning fitted over our desk. Be really careful with single point attachments, there is a lot of force on it. I would much rather go for a trapezoid or rectangle shape and attached along 2 edges.

Our old house had a solid hard wood fascia into which I could screw a row of hooks every 20cm or so and run a decent size rope zig-zag between the hooks and shade cloth clips. On 2 edges the tensioned rope was attached to the shade cloth to reduce the flapping. On the 4th side (timber fence) I also used a row of hooks but used bungy cord instead of rope which absorbed some of the wind load.

For our new house I've 99% settled on the DuraLock2 system (see TradeMe for a reliable supplier) and attach it to the top of our fence and the edge of the soffit where the fascia header is. I will avoid the rafter lookouts, we lived on site when our house was built and the rafter lookouts are poorly attached, just enough to hold the soffit panels up. The rafters will be okay, but you do not know which side of the rafter lookouts they are.

(As I'm not a builder, I'm using terminology from the internet and may not be the same as what you call them: http://www.contractorssolutions.com/fascia_soffits.htm)

My handyman directed me to http://www.retwine.co.nz/outdoor-fabrics as a fabric supplier close to me (in Auckland). I have not looked at price yet, but should be good and my handyman has an industrial sewing machine.