I've got a Waitrose slot booked. I've not hosted Xmas for a couple of years but last time I did, there were a couple of things that were out of stock - nothing major and I was able to pick them up the next day (always get the delivery on 23rd in case of disaster).
Normally, I get a turkey from our butcher but this year, there's not many of us and my mum is set on a Waitrose turkey crown but I'm worried that it might be out of stock on the day because they basically grab your order off the shelves don't they? I spoke to an assistant today and she reckons as long as you can put it in your basket and pay for it, then it will be delivered. But that hasn't always been my experience (as with any supermarket - I don't think Waitrose are any worse). For some reason, my mum is convinced that this general rule won't apply to the Xmas turkey 
What does MN collective wisdom reckon? I can order a turkey crown from the butcher as well incidentally