The short answer is: there are no pre-made adventures for T5, in the book or, as far as I'm aware, otherwise.
The long answer is: players new to Traveller are probably better served with Classic Traveller or Mongoose Traveller rather than T5. I don't have any experience with T5, but it's my understanding that it's closer to a Traveller toolkit than a ready-to-run RPG. Both CT and MGT are ready out of the box and, while neither has an intro adventure in the core book, both have several published adventures available. Both CT and MGT also have a large catalog of supplements available when you're ready to expand the game past the core.