A.V.
Make a list. Cut off the things that are less important. Decide what can be done with you and the kids and what you might need help with (dragging a 9 ft tree in the house?). Get the kids' help. Shop online when the kids are in bed or during lunch. Take the kids to the mall when you can get them alone or maybe team up with another single parent, swap a few kids and help each other's families shop.
My mom was a single mom most of my childhood. We had lovely, if not overblown holidays. It will be fine. :)