Combine the yeast, wholemeal flour, plain flour, bicarbonate of soda, salt, honey, oil and buttermilk into pan of a bread machine.
If baking in bread machine use medium temperature setting.
If baking in an oven, use manual or dough cycle to knead dough. Remove from bread maker and place in a greased loaf tin. Let rise until doubled in size. Bake in a preheated 180 degree C oven for 25 minutes or until bottom of loaf sounds hollow when tapped.