I bought a package and am not sure what it is!
Self rising flour is a sort of short cut flour which has salt and baking powder (chemical leavening) already mixed into it. I know it is called for in some biscuit and muffin recipes.
It seems to me self rising flour is a basic pantry ingredient for convenience in England. I find it called for often in pancake or scone recipes. Seeing it in a recipe can really throw us off here in the United States, but it is available in most grocery stores, and I found directions for making your own self-rising flour by Martha Stewart here
It's a mixture of all-purpose flour, baking powder, and salt.
I only use it for this great bread.
3 cups flour
big pinch o sugar
1 12oz bottle of beer (any)
bake in a loafpan at 375 for 1 hour.