How would the result of this recipe be affected if I were to use all purpose flour entirely instead of all purpose flour & bread flour?

I never use bread flour. I always use all purpose in all my yeast recipes. You will be fine with all purpose.

Bread flour has a higher gluten content, which lends bread doughs that pleasing, slightly "stretchy" texture when you pull it apart. If you have only AP flour, you can probably use that only. The result will be somewhat "shorter" in texture.
Dorie Greenspan in her book, Baking with Julia, for example, uses solely all-purpose flour.