The children won't care about the Xmas meal, though - so really, don't guilt yourself into it that way.
In fact, they'd probably enjoy seeing YOU sitting down with a glass of sherry during the day, getting involved with them and their presents and having a good time.
And in the long run, it will do them MORE good than anything else to not have the 'women in the kitchen/men in the pub' scenario spoon-fed to them.
So - you say - yes fine, everyone's more than welcome. I'm not cooking though, I've done all the work for the last x years. I might come along to the pub for a bit, but I'll probably stay put and play with the kids. So you need to get that organised with MIL/SIL/BIL, see who's going to take it on for a change.'
And then - you don't buy food as usual then leave it until the big day to try and get someone else to cook, because guaranteed you will cave. You make SURE in the run-up, when it's just you and him, that the message gets across that you ain't doing the work - at all - this year.
So, next week - 'Have you spoken to them about who's cooking/buying the food? We need to book lunch somewhere if no-one's prepared to do it'
Week before Christmas: 'I'm going to do a shop for Boxing Day food. No, nothing for Christmas meal, I've already said - I'm not doing it. If you don't sort it, there'll be nothing but snacks.'
AND THEN - THE HARDEST PART - ACTUALLY DON'T BUY THE FOOD.
I predict a panic and an argument on Xmas Eve, which is when you will know whether you actually do have a good guy who will take notice and help you out when given a nudge, or whether you have en entitled lazy user who will turn nasty when he doesn't get it all his own way when that's what he's been used to!