Thanks for you time.

I guess my original confusion was over the creation of 2 setup packages. With the second package really just including changes.

Rightly or wrongly so I'm opting for each install (even minor updates) to be a complete install.

Therefore I only have one installer script, it includes wupdate (recompiled with UAC 'asInvoker') and wucheck.

Anyway what I mean to say is I think I got it working and thank you for your help.

I think the exact issue that I was faced when I originally posted is:
When I 'Internet-based Installation' \ 'enable web installation' I was not presented with the 'features' or install location, as I was expecting.