Hi Nigel welcome to the forum, although I see that you've been lurking for some time.
Nigel A wrote: will my gear be up to the job,
In a word - Yes.
Your 8wt fly gear will be ideal for snook and small tarpon and the spinning gear is spot on for jacks, snook, medium tarpon (up to 30lb say) snapper barracuda (wire trace essential) and bonefish too,if you use small plugs like the Maria Angel Kiss.
If you fancy a crack at bonefish on your fly gear then a wt forward floating #8 line would be better than your shooting head, but I wouldn't buy one especially. Bones are easier to temp on the small plugs and spinning gear.
Have you looked at Mike Ladle's website? I've posted some links to four reports on our May '07 trip in another thread and we had all of the above species from mainly shallow bays, flats and easily accessible beaches from the Coco Reef hotel.
The 12lb mono line will be a little light for some of the species, I would always use either a 25cm length of 30lb wire trace (Tyger wire) or a 75cm length of 40 - 60lb mono if tarpon, snook or jacks are around.
Bonefish aren't put off taking lures if you use wire and species like barracuda, snapper and needlefish (garfish) are capable of nipping through 12lb mono and you'll loose the fish and your lure, so if you fish the flats with your spinning gear, wire is essential.
I would normally recommend 30lb braid as a main line, as it has distinct advantage over mono, but wouldn't recommend that you switch if you haven't used it before. Some people have awful problems getting used to braid, but few would go back to mono once they've mastered the few 'must do's' that you need to excercise when using it.
You might be interested in this YouTube post (with soundtrack).
It was filmed in Tobago and you'll notice that the gear is pretty much the same as yours, so I hope it will give you confidence.
http://www.youtube.com/watch?v=jHIAq60YR5Y
Hope this helps
Cheers
Steve
Take only photos - leave only footprints. I like that concept.