I haven't done any but been to some (mostly organized by integrated FTOs, and I was only there just to have a look at them, I did my CPL the modular way).
A bit shocking if you're done with your training already, but not surprising will be:
Most don't want to hear about Cessnas or Pipers, about training or studying. The majority of students about to finish school still think the glamour factor is huge in aviation. Who blames them, they probably don't hang out at pprune everyday.
They will most likely sit through a presentation, showing what is needed to get a fATPL. They'll see the cost factor and will get the training factors presented. They won't particularly care about the 70k price tag of most courses, and the medical and the studies are just side effects for most.
Then, after you're done with your presentation, they'll ask questions. If you're flying a heavy, one will be:
"How long did it take you to get to fly the 777 / 330 / 340 / 747 / big freaking plane? I want that too!"
If you fly turboprops or smaller ones, another one will be:
"So, why don't you want to fly a cool plane like the 777 / ... / big freaking plane?"
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All in all, I'd recommend giving a good outline of the job, what physical and intellectual qualifications are necessary normally. How does training work, and how much does it cost. Maybe a quick thing on modular and integrated.
Make sure you tell them it will be hard work to land the first job, but also tell them how you enjoy it. How challenging it can be, and how different one flight to the other can be.
All the usual stuff, should light their fires pretty well