If you are just across the street from the bar you are going to, then pop over early and talk to the bar staff and ask them to only give you the virgin version of whatever you order, no matter what, and to still make it up like an alcoholic drink. You can also order Mocktails that are still served up like full cocktails.
People really don't pay as much attention as we think they do. On Christmas Day I was at my in-laws who are big drinkers that encourage everyone to drink like they do and I managed to get away with a champagne glass of Appletise which I topped up from the bottle I stashed in a cupboard and no one batted an eyelid.
Good luck and happy new years!