Christmas: I had a similar upbringing to you pass. My mum had very little and saved all year to make Christmas magical for me and my sisters. It is only looking back now that I realise just how much she sacrificed for us, she really is an incredible person. If I can be half a good a mum as she is I will be winning.
Anyway, we had loads of traditions, lasting the whole month of December. We had a homemade advent calendar with activity cards for the whole of advent put in. Anything from making Christmas cards to tearing up xmas catalogues to make santa lists. Christmas morning was always a fantastic time of wearing new Christmas jammies and taking it in turns to watch each other open presents, whilst my mum frantically wrote in a notebook what everyone received and from who so we could write our thank you cards in the days before we went back to school.
Since leaving home, I have always hosted an 'open house day' sometime over the festive period. This started in my flat in Aberdeen and correct me if I am wrong but is a Norwegian tradition (my flat mate was from Norway, this may just have been his family tradition!) Anyway, we open the house from about midday and kick out the stragglers at midnight. People come and go all day and eat, drink and join in the craic. People bring a bottle and food offerings and we always have to much of both. I love it!!
Food. When we are skint we cut back on squash, coffee pods and buy cheaper cuts of meat. I dread to think what my weekly food spend is at the moment as we are far too guilty of doing wee fecky shops. But yeah, meal planning and Costco card abusing is definitely the way forward. We spent about £50 (max) on Dettol, fairy non bio washing liquid and softner, dishwasher tablets, loo roll and kitchen towel in March and they are all only just running out now! Our downfall with Costco though is wee always go mad on wine and cake 
Also dog food. On recommendation of a vet friend, we switched Aulay to Wagg. It is commonly perceived as cheap crap but is actually one of the better foods in terms of vitamin and protein proportions. Anyway, it costs us about £2.50 a week to feed him now!
Also also, and I will stop but I love bargain hunting(!), we buy Tesco's 'Cheeky bots' nappies when they have a baby event on. On offer, they are £15 for a month's supply. I usually buy 2 boxes and that does us until the next baby event. Pampers wipes (the only ones she doesn't react to) are bought in bulk from Costco.