P&O Cruises are operating a number of charter flights from London Gatwick to Santiago.
The aircraft will be
Monarch Airlines Airbus A330-200, with a stop in Cuba
Thomas Cook Airbus A330-200 with a stop in Barbados
Britannia Airways Boeing 767-300ER with a stop in Barbados
It depends on your tour operator on which aircraft is being used etc.
Ps. I know this, as my sister is the head of flight operations for P&O Cruises UK.