If you add an item to your basket and get a ‘sorry, it’s not possible to check out with this product at the moment’ message, it means the item has sold out and our website hasn’t finished updating to show this. This may happen with Limited Edition releases where a large volume of Guests are trying to check out with a particular item.
Try clearing your cache and cookies or checking out as a Guest for a better checking out experience, and make sure your payment details are up to date.