Re Christmas: I'm a moderator rather than an abstainer, so I can cope with a day it even two "off piste" without completely falling off the wagon.
The problem with Christmas is that the temptation lasts for longer than that 
We have our main Christmas Dinner on Christmas Eve (from my dad's Danish heritage).
I tend to fast for most of the day before having bubbly about 6.30 to celebrate everything being ready I hope 
Starter is home made tomato and mint soup (ingredients: tomatoes, onions, mint and a glass of Sherry, finished off with a swirl of cream).
Main is citrus bribed turkey with a citrus gravy (that doesn't even need flour to thicken it although I've put a tiny bit in in the past), home cooked glazed ham on the bone, roast potatoes, mashed parsnip with chopped chestnuts and Savoy cabbage with crispy bacon bits. I usually have just one potato (and often don't finish it) and a small spoonful of the parsnip.
Dessert is the Danish Christmas pudding: a sort of sweet rice risotto with chopped almonds and whipped cream gold through it with one whole almond (whoever gets that gets the almond prize). I do have that 
On Christmas Day, I'll have one sourdough croissant with bubbly while we open presents. Then in the evening we have more tomato soup and then roast pheasant with the same veg as the night before - and again, I might have a potato but I won't finish it. In theory we then have home made (British) Christmas pudding served with my concoction of vanilla custard mixed with whipped cream but in practice we're usually too stuffed from the night before 
I also have snacks of killer almonds (made with butter, garlic, spices, Worcestershire sauce and Tabasco - made in advance and stored), "turkey bites" (canapés which I've adapted to be fully low carb) and plenty of cheese.
The next couple of days we tend to snack on cold ham and turkey. New Years Day we traditionally have a big fry-up with Stornaway black pudding and good quality square sausage.
The risk is the tin of Quality Street. I'm usually ok for a day or two (will taste my 3 favourites and then stop) but if dh and ds don't finish it quickly I get tempted 
I also make very good mince pies
. I'll allow myself one and then I'll keep the rest in the freezer so that they have to be warmed as weirdly I don't like warm mince pies. 
This year I'm also going to make myself a supply of the cheese or vanilla almond based muffins which can be toasted to have as a snack if/when I'm tempted. 
I do keep weighing daily from Boxing Day onwards to try to keep myself accountable - but may end the Festive period up to 7lb up
. I'm getting better each year though.
Not perfect - but I don't feel deprived and I feel I've managed to balance my low carb WoE with the Festive Period. 