I can now reveal to you that the Holy Father was served Macsweens haggis at his lunch in Edinburgh on 16 September 2010. Macsweens are the Guardians of Scotland's National Dish. You may purchase this excellent product at any of the following supermarkets.
I will leave it to Mrs Jo Macsween to help you decide what type of haggis to buy.
Perhaps you were expecting me to recommend you purchase your haggis from Donald Russell - suppliers to Her Majesty The Queen of Meat and Poultry, but in fact they will simply supply you with Macsweens haggis! So, just go to Tesco or whichever supermarket you find most convenient.