I'm not a smoker but if I remember, I think they asked in the beginning of the tour if anyone in our group was. Besides lunch, there are at least 2 potty breaks during the tour.
I also recommend bringing a bottle of water and a small snack with you. I brought small bags of peanuts and was grateful I did. DH & I are not big breakfast people and we didn't really have time to grab a snack mid morning.
They gave us bottled water in the beginning of the tour but I'm glad I brought another one with us as it was a long 5 hours.
Well worth the money though. I personally loved, loved this tour.