So this past week I started an 80 day workout program and I just realized that I'll be on our cruise during the 3rd phase of it

I'm being realistic knowing I'm not going to care too much about nutrition that week. I mean I'm not going to eat 3 Guy's burgers a day or anything, but it's also vacation and I'm going to enjoy it.
Anyhoo, I'm going to really try to get my butt to the fitness center each morning. My question is: does anyone know if you can use that fitness room where they have classes if a class isn't going on? I don't think I'll have any room on the regular gym floor. If the day doesn't call for any weights, I could maybe use one of the clubs/bars that are empty in the morning? Do they lock those rooms?
I figure I'll try my best with this but also stay realistic and if I need to start my "phase" when I get home then so be it.