not a lot really. Make sure there’s enough toilet paper in mainly, and that the cat hasn’t shit on their bed.
when they arrive make sure they know where tea and coffee etc are, and tell them to help themselves to anything - treat it like their home.
Then i persuade them it’ll be really cute for the kids to wake them up at 6am and that they should go downstairs with them and play as its the “best time of the day” - give instructions about the bottle and everything. Then i go to bed for a massive sleep.