It's very expensive, you might want to stick to free WiFi and messaging apps.
|Data||£5 per MB|
|Calls & voicemail (charged in per second increments after first 30 seconds)||£1 per minute|
|Receiving calls (charged in per minute increments)||£1 per minute|
|Sending texts||30p per text|
|Picture messages (MMS) to a UK/EU mobile||16p per MMS|
|Picture messages (MMS) to any other mobile||24p per MMS|
For roaming in the Bahamas:-
giffgaff say "Roaming coverage cannot be guaranteed in this destination, and some services may not be available" - see https://giffgaff.com/roaming-charges just below the roaming rates.
If you look at http://international.o2.co.uk/internationaltariffs/travelling_abroad# O2 say Pay As You Go roaming is "Unavailable" there.
So giffgaff is extremely unlikely to work correctly & fully in the Bahamas (although some parts of the service may function).
How can I use my phone in the Bahamas
It will be very expensive.Use free WiFi and an app like WhatsApp and or buy a local Sim card when you get there.Bookmerk this page and download for offline reading just in case,