If one of my family did to me what the OP's DH has in mind, I would be sorely tempted to say 'No room at the Inn' and close the door on him.
What happens if the family, instead of greeting him with the delight he is expecting, look at home aghast, and say' Why on earth didn't you tell us you were coming?' What happens of rows and tears happen because of the inconvenience he is causing, because someone has probably got to provide you with a bed for how many nights? bedrooms may need rearranging, beds remade.
Has he made any atempt to see if he will even be able to find a hotel for the night. Most hotels will either be running Christmas packages for people wanting Christmas away from home, with meals, or they will have closed down for the Christmas period. There will be no hotel rooms available.
The family saying 'When are you coming down to see us again' is not in any shape or form an invitation to turn up on the doorstep on the biggest day of the year, 2 of you, expecting to be greeted with joy and the whole day turned upside down trying to find space at the table and somewhere for you to sleep.
There after this Christmas will feature in family history 'as that awful Christmas when x &y just turned up on our doorstep just as we were sitting down to lunch, and we had to disrupt everything to extend the table, find cutlery and china and we didn't eat until everything was cold and had to be reheated - then they wanted us to give them a bed for the night!!!!