cammomile tea? its supposed to make you a bit drowsy, and has zero calories. Its a bit funny-tasting, but you can buy 'cammomile & spiced apple' flavour tea (twinnings) which tastes of cinnamon and is much nicer.
Although alcohol, glass wine/ toddy does seem to get you off alright it seems to interfere with your sleep patterns and make you wake up later on. So stick to your milky drinks, lots do a light version these days that you just add hot water to so are not too high in calories.