Thanks for the reply Domy Dom.
Although we have booked through TC themselves, it seems even they don't have a definitive answer. Given that we are traveling next month, it seems as though they have some doubt that this 'new aircraft' will arrive on time (or maybe fitted out on time). I guess by the time you go in the Spring that should be resolved.
In the meantime we are in limbo.
I find it a little odd that we are a group of people able and willing to give TC more money for a better product and they are still struggling to take our money!
Hopefully someone in TC will read this and advise.
Enjoy St Lucia!!