There are subtle differences in the ingredients for each different sized bar, as they come from different suppliers. This ingredients list is fairly typical:

Milk Chocolate Bar 40g℮   Ingredients: Sugar, Cocoa Liquor, Cocoa Butter (Cocoa Solids min 35%), Skimmed Milk Powder, Milk Fat, Whey Powder (Milk Solids min 14%) Vegetable Fats, Soya Lecithin (Emulsifier E322), Natural Vanilla Flavour.