You can't make the connection at UVF, I often go to Trinidad (it's where I'm off to next week) and sometimes there is avios availability to UVF but not to POS and they don't let us book the connecting flight separately. It's only an hour on the ground.

Also be careful, there are two airports in St Lucia SLU and UVF and they are about an hour apart.

If you can make flights work, BA fly ANU-TAB, but think that's only once a week at the moment. If it's twice, you might be able to squeeze Tobago in and its beautiful...

Grenada isn't a bad shout if you're down there too..

Trinidad is very industrial, not your typical holiday place but if you like partying, warm weather and interesting things to do (like Pitch lake, bird watching), it's worth a few days.