You can get yourself a free Thornton's advent calendar at Thornton's from TopCashback. Just follow the link to TopCashback, register your details and purchase the product through their link and you will get £15 cashback on a £15 spend.
Click on “GET IT HERE” button, create a free account on TopCashback, use their link to visit Thornton's page and make a purchase. You will get 100% cashback for the amount you spent.