"Hagrid," said Harry, panting a bit as he ran to keep up, "did you say there are dragons at Gringotts?"
"Well, so they say," said Hagrid. "Crikey, I'd like a dragon."
"You'd like one?"
"Wanted one ever since I was a kid –– here we go."
They had reached the station. There was a train to London in five minutes' time. Hagrid, who didn't understand "Muggle money," as he called it, gave the bills to Harry so he could buy their tickets. (Harry Potter and the Sorcerer's Stone)
Does the phrase mean ‘let’s go’ or ‘said when something bad starts happening again’? (I guess the latter is more likely that Hagrid seems to blame himself.)