Sorry if this is an obvious question! I've just started expressing so that DS can occasionally be fed by someone else, or so we can take a bottle out with us if we're somewhere where I don't want to breast feed him. I have an insulated bag for the bottle to keep it cool, but I guess I then need to warm it up before feeding it to him? Fine if I'm near a hot tap, but what if I'm not?! Say in a cafe, shopping centre, or out on a walk or in the park. What does everyone do?