Melt butter in saucepan over low heat. Whisk in flour and stir until incorporated. Allow to cook for 1-2 minutes until golden in color, stirring often. Whisk in milk and increase heat to medium. Cook for 2 minutes or until thickened, stirring often. Add in cheese.
Remove from heat and stir until cheese is melted. Use a metal stick blender to further emulsify the mixture if needed. Add Worcestershire sauce, paprika, cayenne, and white pepper. Add salt and pepper to taste.
Arrange bread on lined baking sheet. Add 3-4 slices of turkey followed by 2 tomato slices on each piece of bread. Sprinkle tomatoes with a little salt.
Divide cheese sauce between each piece of bread, pouring it over the top. Add 2 bacon slices to each sandwich. Set oven to low broil. Bake for 4-7 minutes or until cheese sauce bubbles. Serve while piping hot.