Hi Ruthy, I am also travelling to St Lucia on 5th Feb 2024 & will be staying in premier in near T5 on London Road, Crawley, the night before, not sure if that's same one your in? I don't know what time I'll arrive depends on trains & I have to navigate my way from Kings Cross! As far as currency they use Caribbean dollars but also will accept US dollars in restaurants & bigger shops but exchange rates may not be to good, market stalls & small business need local currency!
Not sure about plugs someone else may be able to help there!
looking forward to meeting you & others on trip!
Sheila (from Newcastle)