Have bagged a slot, but whilst I do year round grocery shopping via tesco normally, I've only had one Christmas delivery and that was a few years ago. Didn't repeat it as there were so many important Christmas items out of stock (think stuffing and sausages in bacon- shock horror) that I haven't trusted them since.
Have things improved? Can I rely on mr tesco or sainsbos to deliver what I've ordered? Or do I really have to schlepp round the local morrisons at 6 in the morning to make sure I get the fresh goods I need?