I am sorry that your family is unsupportive. That stinks. I can't understand it. I wouldn't wait around for your AH to decide whether and when he wants to see the children. Make plans if you can. If he calls at the eleventh hour, are you comfortable saying "sorry, I didn't hear from you. we made plans." Or something along those lines?
Holidays with alcoholics really aren't very jolly, are they? Hard to get into the spirit of things.
Hugs.