Sophie, I don't know if there is any way you are going to be able to control that on a cruise. The only way that I can think of is to eat only at the buffet and to eat only plain meat. I am booked for a cruise a year an a half from now, and my thoughts are that I will do what I can to avoid alcohol, but I'm not going to ruin my vacation over it. I and my DH will know that I did not drink and that is what is most important.
Also keep in mind that hand sanatizer is EVERYWHERE on a cruise ship due to Norovirus outbreaks. I'd be more concerned about avoiding that stuff!