Are you confused by all of those answers, Smurfchops? The correct information has been provided but, in case you're still confused, I'll try to sort it out for you.
When making any international call, the first thing you need to do is to start with the number that accesses the international exchange system of the country which you're dialling from. That varies between countries. In most of (but not all of) Europe, including the UK, that's '00'. From Antigua & Barbuda, the Bahamas, Barbados, Dominica, the Dominican Republic, Grenada, Jamaica, St Kitts & Nevis, Saint Lucia, St Vincent & the Grenadines, and Trinidad & Tobago it's 011, but from Cuba it's 119 and from Haiti it's 00.
Then you dial the code for the country you require. For the UK that's always '44'
Lastly you dial the full number of the phone. In nearly all countries (including the UK) where a leading '0' forms part of the number, it should be omitted.
So, from the majority of Caribbean countries 01234 456789 becomes 011 44 1234 456789.
You'll see, from the above, that it's the first part of the international number which can be tricky. (If you're in a strange country, you might not know the international access code from that country). However most countries telephone systems now recognise using '+' (from your mobile phone) as an alternative way of dialling the international access code (so you don't need to know what that code actually is). Assuming that the Caribbean systems recognise that system, dialling + 44 1234 456789 should also work.
Chris