Have you researched your area for a good bakery that can bake your bread. If you're volume is great enough a good bakery will
make you an exclusive bread that is not available to others.
I've been involved in putting together business plans for a variety of sandwich companies. I have yet to find it financially feasible to produce sandwich bread on-site unless it's a multi unit company which uses the one facility to produce for the others and that's still tight.
Factoring in the equipment, labor, space, utility usage, it just increases the cost of your bread to where it would not be comparable to outside
Unless of course you are planning to have a full bakery outlet as well as sandwiches.