For those that struggle this is what I do for my 3 children, they don't have granny, aunts, auncles, cousins that buy them gifts so Christmas presents are only bought by me, list is up thread.
We get paid monthly so after bills I work out what is left for each week and thenbwork my food budget out, leaving some money spare for diesel and spends.
If I don't spend a weeks shopping money (tries very hard by using a meal plan) what I have left goes in the Christmas box (can be between £2 - £20)
Child benefit is included in our monthly amount so I spend that on food and children's needs.
I shop through cash back sites and use Sainsbury petrol station to build up points on that card and tesco online for food to collect vouchers for Christmas. Any extra money I get along the way, EBay, netmums, facebook selling goes away for Christmas.
I also have a staff bonus scheme that I get high street vouchers with so I save them up to.
I then get on here and join the bargain thread around Sept\aug and pick up the bargins that way,for example the paper Jamz rrp is £30 I got them in a flash sale for £5 each through a cash back site.
It means I get more for the money I have saved and that their main present isn't bought with cash cause I use points, vouchers and cash back that I have saved through the year.
Www.moneysavingepert.com has been very useful but the Christmas bargins thread has saved me the most money and bumped up what I have bought with some great, cheap fun ideas. The Christmas hamper is going to be great tis year and cost me £10 per child.
I don't use credit cards and am in no debt for Christmas, still got food to buy but we could live off chocolate at this rate, half price Thornton selection boxes cheaper than 3 normal ones in home bargins.
Hope this post helps give someone some planning ideas for next year, as soon as the last bin bag of wrapping paper is in the wheelie bin I'm starting to plan for 2013, birthdays aren't a big thing here just cake and a gift from us and we don't go in for holidays because of work commitments so Christmas is my one time a year that I can sit back and spoil them rotten, they are great kids most of the time so deserve it 
Asda have sponge bob square pants magic flannels for £1 and bath crayons.