When I'm out and about I often don't take any alcohol with me for a variety of reasons; It takes up space and is heavy, sharps and booze don't mix, I don't really fancy it when out and it enhances iron intake.
However that said, if you have a cool Autumn evening then mulled cider (or straight apple juice) is quick easy and very warming. This crusader cup has a measure of cider being infused in it's simplest form, literally it is slowly warmed through, never boiled, with a hint of sugar and half a cinnamon stick in it.
Or for a more developed flavour use a hint of sugar and a mulled wine teabag type sachet that can be purchased in the shops, especially on the winter run up to Christmas. And talking of Christmas you can experiment with the additions, just think of any spice that might go into a sweet Christmas dish as a rough rule of thumb.