Of all the ways you can cut your costs for christmas, food and drink is probably the hardest, as the costs are fairly fixed. There are however a few shortcuts you can take.
Most supermarkets carry value ranges, many of which are surprisingly edible, and you can save plenty of money by purchasing these cheaper products.
You can also eat less - sure, eating a bit too much and crashing out on the sofa in front of Moonraker is half the fun of Christmas, but why not try and scale it back a bit this year?
For the main meal, you might also want to consider a chicken instead of a monster turkey. There's a nice recipe here for a Christmassy chicken.