OP, given that you probably don’t have time to leave your DH or effectively adjust his behaviour and usefulness before the party, I suggest you prioritise whatever will make the party successful for your D.C.
Rope in your Mum to help, if she will actually be helpful. Ask her to meet you at the venue and help set up, occupy your Dc while you set up.
Have everything ready the night before. Trays of food, or however you are doing it. Go for the easiest option for everything.
Be friendly and welcoming to FIL, don’t stress at DH because it won’t make him any more cooperative. Just say “obviously we will have a really tight timetable so I am leaving in the car dead on 5 to 9. And do it, calmly. If they have to walk or get a taxi or miss it, so be it.
IF there is any chance of help say ‘oh FIL how lovely to have you here, Dd will love to play with you / blow up balloons while I set up’. Or ask DH what things he would like to do.
Bedding etc: just sort your or. Stuff out and say “FIL’s clean bedding is on the landing”. Etc.
But basically, make lists, take the easiest option, plan to be able to do the party without help. It can be done, honestly.
Then congratulate yourself on how well you did it all and think about the longer term.