Guess who else is coming to dinner....

So I've made the mistake of inviting people from work over for drinks on the balcony and told them I'd give them food. I have no idea how many people are coming, what time people will leave etc. My biggest fear is not that I'll run out of food... or even that no one will bring a chair to sit on. My biggest fear, no make that fears, is that I will a) run out of toilet paper and b) that people won't respect the unwritten toilet door rule.