The night shift would involve pulling stock (from the deliveries) to be packed out in the morning, probably doing a good bit of packing out yourselves, making sure the entire store is immaculate and doing returns from the fitting rooms etc. Not a massive amount of fun. Primark have nightpack all year round, they hire hundreds of christmas staff per store, just keep the head down and do a good job and you might be kept on. If you were, you would not immediately be given a permanent contract but another temporary one.