Though unconfirmed, this is believed to be for a forthcoming episode to be filmed that has been written by Gareth Roberts, who also penned Craig's previous appearance in the series. Roberts was a guest at last weekend's Gallifrey One convention, and during a live commentary for The Lodger was reported as saying that his new episode would begin filming "in a week" (i.e. from next week).
"I work in a shop, now."
The news comes after a tweet was posted yesterday unofficially revealing that Corden would be coming back to Doctor Who: "They're filming Doctor Who with James Corden the whole 2nd week of March on my street. Just saying."