Atlantic Star Airlines were going to use a Dutch registered TUI Boeing 737-8 for there planned service to St Helena NOT a Boeing 747, for a start TUI do not fly the Boeing 747 only Corsair of France do and they are not part of TUI anymore.
Unless that's a typo error!
BTW it's just plain TUI not TUIfly, the 'FLY' part was eliminated a long time ago even though many like to add it as in here in the UK many still call it Thomsonfly to TUIfly when it's totally incorrect.