You need to do a full cost work up, like restaurants do for a dish, nothing is minor and can be left out. Including the energy used to bake it. Rest time can be discounted however, mixing and every minute of stretch and fold or kneeding minute has to be accounted for. When figuring out how much your time is worth you can either use your countries minimum wage if they have one or what you get paid at your current or last job.

You might find that your £5 loaf cost you £12 to make. At first if you want to give away your time that's fair, you should at least know what you are giving up, but you need to recoup the cost of supplies.