Unfortunately I'm unable to make useful input due to lack of experience of growin enough vegetables, let alone the Christmas ones.
Hopefully I will learn a lot for next year Christmas by the end of this thread.
I think if you can make your own cranberry sauce, you should. I had a jar of an exclusive type as Xmas present and the taste/texture was just splendid...not cheap jelly-like you get from the everyday quality of cranberry sauce. Maybe a good idea to get a cranberry bush between now and spring for 2008 Christmas dinner.
For potatoes, they say Vivaldi is the no 1 best tasting tatties but it is a new potato. I tried them when they were half price at Sainsbury and got my tasters to give me the verdict (since I'm no good at telling) and they said it's a very tasty potatoes with full of flavour. I found the texture quite velvety too. So I think they make a lovely luxury item to have for Christmas 2008.