I've put together gas charged engine lid strut kits for many forum members previously for sw and aw's, was also looking to put one together for the bonnet but wasn't happy with fitment (even with a kit that I had bought from another vendor to test fit) and then got sidetracked with other stuff that took priority.
There are a couple of kits selling online but don't recall any being aw specific; the tricky part with the bonnet kits is working out the correct ball joint sockets that will allow the bonnet to close without the fitting rubbing on the inside lip of the guards, most of the aftermarket kits have the edges of the sockets grinded down for clearance but even then it's not ideal. They generally use sockets on each end of the strut that replace a bolt on the guard and one of the bolts on the bonnet hinge and allow the strut to sit in the small gap between the bonnet and guard once closed.
I may look into this again in the near future, but have much rathered driving the car lately than working on it :)