"Hello, what's this?"
Jack hadn't expected to find himself in a-- Yeah, in a spaceship-- but that, he guessed, was Cardiff for you. Just his dumb luck to fall through the rift. He wonders if the Doctor noticed.
He doesn't recognise the design on the ship, which is a little worrying, but not impossible. Although given the last year of (subjective) time...
"I wonder when I am?" In his experience, it's far more important than where.