Oh yes, the Voice.... 'You'll be fine, you've come this far, you've proved you can do it now, one won't hurt, go on you know it'll be fine..'
Nightmare isn't it ?
But it does go away eventually, I would suddenly realise I'd not thought about it for a day (subsititute minute/hour/week as applicable) then I found I'd be obssessed again for a while until I was distracted.
Northerner, I'd be seriously tempted to not go this time or rebook into somewhere which only allows smoking away from the tables - our local Chinese lets people smoke in the waiting area near the bar but that's all.
But then my willpower is deeply suspect, even after 5 years (this time) I had to be careful at the last MN meetup I went on.
Stick at it guys, it's a tough few weeks/months but as a proportion of the rest of your (longer) life it's not so much. If you do fall off though jump straight back on if you can. Good luck.
I'll leave you with a loud outburst from dd in a DIY store last week:
'Mummy why does that man smell so disgusting ?'