Warm 1.5 kg of white bread flour, with the self-raising flour and instant oat cereal in the oven on gas 1 in a large metal pan first.
Activate 15g yeast according to instructions on packet. If your packet does not specify, activate by mixing the yeast and 1 teaspoon of sugar in a small cup of hand-hot water, leaving it until it forms a foamy head as is shown in the picture.
The water temperature should be between 105° F. and 115° F. Use an instant read thermometer if you have one, if not, test the water against the inside of your wrist by holding it under the tap it should feel very warm but not hot.
Add salt to the warmed flour.
Add about 2½ warm water (including the water in which you activated the yeast), gradually until you get a not too slippy dough.
Mix by hand, or with a spoon. No need to knead.
Put a fifth of the dough into each of 4 of your 5 greased or lined loaf tins. Silicone loaf tins are great if you have these already.
Add the ginger, sugar and garam masala, to the remaining fifth of the dough and mix well.
Put this mixture into your 5th greased tin. You can use a 10 inch round cake tin, or pyrex dish if you don't have a fifth loaf tin. Leave in a warm place to rise for 40 ish mins til dough peeks about 1 cm above the top of the tin. (The ginger loaf may not rise as much as the others, don't worry, just pop it in when the others are ready!
Bake for 25 mins on gas mark 6, or until browned on top and sounds hollow when tapped with a knuckle.
Notes
NB if you are cooking fewer than 5 loaves (4 plain, and a sweet one), always use at least 10g yeast even if you reduce all the other quantities.