As you’ve said “do not fancy”, I will assume you aren’t speaking SAE :0) so do you mean “Holiday” as in Christmas or “Holiday” as in Vacation?
That aside, the crucial point is to have a plan. Think of the what ifs and plan how to address those. If I’m offered, what do I say? If I’m pressured further? “Oh come on, you’re on holiday. It doesn’t count.”
You know your audience best, so you’ll know their angles. My go to answer is “I can’t. I’m allergic. Alcohol makes me wake up with Ugly Women.” It seems to defuse most People w humor…except the Ugly Women. They always seem to get VERY offended :0)