For 3 loaves of bread you will need:
1 and 1/2 cups of sourdough
3-4 cups of water (depending on your flour)
9 cups of flour
1 tablespoon of salt.
Making sourdough bread is not hard work it just takes a long time. You will need to pick a day that you are home because it's a whole day project.
Starting in the morning I'll set here some times as a reference.
8.00 am: Mix the sourdough and the water, pour the flour, add the salt and knead the dough until it's all well mixed. You don't have to mix for a long time, just enough to make sure it's all mixed well. Start with 3 cups of water and add some more to make sure you have a nice soft dough.
8.00 am to 12.00 noon: Knead every 45 minutes by taking from one side and bringing to the middle and then from the opposite side. Then turn again from the other two sides and repeat this process 3 times. Let it rest in between and cover the dough so it doesn't dry.
From 12 noon to 4.00 pm: Let the dough rest
4pm: Lightly flour a counter, pour your dough and divide in three parts.
Grease your tins, knead each piece in the same way as before, shape and place in the tins. Place each tin in a plastic bag (the dough will probably rise above your tin so do not cover with film as it will restrict from rising).
6.30 pm Turn on your oven at 180 degrees (if possible, fun and heat from the bottom). If your oven has steam use it, if not place a pan with hot water in the bottom of the oven. Bake for 40 minutes.
7.10pm. Take the bread out of the oven and let it cool
8.00 pm: Enjoy a slice of crusty, gluten free, sourdough bread.
For information as to why sourdough bread is gluten free see here: https://glutendude.com/not-gluten-free/is-sourdough-bread-gluten-free/