Mix the flour, salt, milk & oil together in a bowl, add the water & mix to a soft dough, adding a little more water or flour if necessary.
Knead until it has a smooth spongy texture, about 5 minutes. Cover the bowl with a tea towel & keep in the fridge for when you will use it (or up to 48 hours).
Divide the dough into 10 balls. Scatter your work surface with a little flour. Roll out one ball to a round (or oval) of about 15 cm. Heat an ungreased non-stick dosa or crepe pan. Add the chapati (or 2 if they fit), flattening out any folds which might have formed. Using tongs, check the underside & when a few deep golden spots appear, & they puff a bit, flip the chapati over & cook the underside. Wrap in a tea towel to keep warm while you roll and cook the rest. If you like you can brush the ready tops with ghee before wrapping in foil.