Line a bread tin with parchment paper and lightly oil. Set aside. Preheat the oven to 275°F (135°C).
Add the oats to a baking sheet and toast for 15 minutes in the oven.
1 cup rolled oats
Meanwhile, add the water, 1 tablespoon of honey, and yeast to a large mixing bowl. Mix well and set aside to bloom, about 10 minutes. The mixture should look foamy.
2 ¼ teaspoons traditional yeast, 2 cups warm water, 3 tablespoons honey or maple syrup
Add the remaining honey, salt, oil, and toasted oats to the yeast mixture and stir. Set aside to let this rest for 10 minutes to allow the oats to absorb some water.
3 tablespoons honey or maple syrup, 1 ½ teaspoons fine salt, 2 tablespoons oil
Add the bran and 2 ½ cups of flour, and stir will to form a shaggy dough. Turn out onto a work surface and knead with the remaining ½ cup flour until smooth and elastic, about 5 minutes.
2 tablespoons bran, 3 cups whole wheat flour
Roll the dough into a log and place it into the prepared bread tin seam-side down. Optionally brush the top with a little milk and sprinkle with some more oats.
Bake on the centre rack for 15 minutes at 275°F (135°C) before increasing the heat to 350°F (180°C) and baking for another 35-40 minutes. The bread should sound hollow when tapped once it's ready.
Cool for 10 minutes before removing from the tin and cooling fully on a wire rack. The bread will keep for about 5 days at room temperature and freezes well.