John, the higher rail is your main awning rail that you need to use. Several manufacturers make model specific awnings and anything that says fits a Puck L, Puck 230, 225 or pre 2010 Familia 310, 320 or Pan/Pan Duo should fit.
You can usually pick up a nice older traditional style awning, eg Soplair, Van Der Horn, Clairval etc for £200.
Some owners like the lightweight drive-away low height campervan style that can be had new for little more.
My advice would be spend some time with the forum search facility and picture gallery to see what takes you fancy.
It might be worthwhile having a look at this Sunncamp Swift Verao 260 Low Initial Findings
Colin