There have been plenty of other "plain talking" replies on the thread, so I am sure you have by now gleaned the general consensus of opinion on the matter,
My own observation, and it's one that has been said a lot, is that you do seem to have a sense of entitlement over the child, and a deep resentment towards your daughter in law.
"doing every thing in her power to keep me away"
"She doesn’t invite me around when she’s on leave"
"And now she intends to keep my grandchild at home on Christmas morning when in the past she has come to my home to celebrate "
"She’s booked my grandchild into full time daycare"
"more alone time with my only grandchild"
There is no negativity voiced towards your son, only to his wife. I would say that your grandchild has two parents, and they have BOTH decided to put the child into daycare, they have BOTH decided to stay at home for Christmas morning, instead of (presumably) BOTH coming to your home for Christmas morning, and ultimately no grandparent has the right to have alone time with a grandparent. I assume your son is working, so maybe his priority is for him to have some alone with with his child.
I think you need to take a small step back, and accept that they are no longer "just" your son and daughter-in-law, but a little family unit of their own, and must be free to make their own choices.
I am assuming this is the baby's first Christmas, so it's all very exciting to the adults - to the child, not so much. Just another day, but with some lovely bright wrapping paper to play with.
You are going to see them on Christmas Day, so please, enjoy that wholeheartedly and don't let your resentment build any further, until it reaches the point of estrangement.