So I've had the game from GOG for a while, finally got around to playing it, after an hour or so mucking around I decide to flick through the PDF manual. The manual claims I have the Gold Version which include Unfinished Business, but I saw absolutely no mention of it being the Gold Version on the site, as well as seeing no reference to UB or a Gold Version when I was playing the game (well except for an "Iron man" option when I started the game which the manual suggests was added in Unfinished Business.)

So basically, what version DO I have? I suspect it ISN'T a version with UB and the manual is misleading me due to the fact that UB is available for purchase off the site.

JA2 Gold Edition was a 2cd package, with CD1 being JA2 patched to version 1.12 and CD2 being JA2:UB patched to 1.01 or 1.02, not really sure which version. Thus the manual for the gold edition should be up to date for JA2, but Unfinished Business isn't included with the JA2 GOG.com sells.
If you find any mod which recommends you to install JA2 Gold Edition, GOG.com's version should be ok.

Thanks, that's cleared that up :D