Try the following method...it works for me.

Each year I follow the same 'shopping list'..when I pack the decorations away, I put the list in with them.

I put my decorations up on the 1st December. That way, it gives me plenty of time to arrange the 'food' shopping. I will list some the items on my list...
Turkey, bacon, potatoes, brussels, Chestnuts, sage, parsley, onions, butter, bread, gammon, vegetables, prawns, tomato sauce, tinned red salmon, smoked salmon, dill, soft cheese, double cream, brandy cream, custard, yorkshire puds, honey, cloves, spirits, beer, mixers, ...you get my jist.

Along side each item, I place 1,2,or 3 or I leave it blank.

3= Buy the item 3 weeks from Christmas
2= " " " 2 " " "
1= " " " 1 " " "

If it is blank, I know this item will need to be bought the last shop before Christmas.

Ie, the Turkey will need to be bought/collected Christmas eve. Potatoes and other veg will be blank. Cream and other dairy produce will have 1 because they will have a 'use by' date usually for a few days after Christmas day. Prawns will have 3 because I use frozen...and so on.

I write 4 lists, one for each of the weeks and hey presto...no last minute worrys.

Ideally, your 'last' most dreaded shop will be just the handful of vegetables and salad stuff....

I follow this method every year...and it works.

Also, in the 'Christmas Bag'...(the back I put away with the decorations)...I put all the left over crackers, serviettes, paper plates, christmas cards/wrap/tags and recipes. So, when you pull them out on December the 1st you get a pleasant surprise...'oh, I forgot I had that...'...it will save you buying it again!!

Good luck, and merry christmas.

UPDATE: 01/12/00

My other half got the tree and
decorations down from the loft this morning...and I looked at my 'recipe' list...I had written down:
Turkey cost £35.00 from Willets
Gammon cost £19.00 from Mandys (an Irish shop near I live...we always get our gammon from there..it is the leanest and best we have tasted)..cook for 5 hours Gas mark 3, Cloves =13 Honey=1/2 jar of clear....

Now, I know how big a turkey I should get and how much it will cost... and the same for the gammon...so handy!