Q.Patio plum tree
Bought the patio plum tree last year. Pruned it when we supposed to. This heat there appeared to be several buds on the tree but nothing has happened with them and now they are oozing sap like orange goo. Does this mean we have lost the tree or is there anything we can do.

This does sound like a bacterial or fungus disease.
It will take further inspection of the tree to make a determination and how to treat; or if you may need to remove the tree.
This article will help you access the tree.
https://www.gardeningknowhow.com/edible/fruits/plum/plum-tree-diseases.htm