For a basic loaf the cost of ingredients works out as per:
Flour (Lidl Strong Bread Flour) 69p per bag (currently priced) Makes 3 "large" loaves
Dried Yeast (Morrisons) 8 sachets (1 per loaf) 80p
Teaspoon Sugar, pinch of salt, Teaspoon olive oil, Water from tap.
So in theory we are, at current prices, making a loaf for about £0.43
Remember that other "brands" of flour (Hovis for example) currently cost well over a £1 a bag.
For some reason known only to the German mind Lidl sell bread flour but not yeast