Are you really planning to decorate or not decorate depending upon what a bunch of random strangers on the internet post to your thread?
There are people who post here who have seriously lacking conscience formation who think almost nothing is a sin, some who are Catholics and some not.
There are people who post here with mental health issues and may also lack proper consciecne formation or suffer from scrupulosity who think nearly everything is a sin.
I suggest you connect with your pastor and ask him to help you form your conscience properly regarding servile work and Sunday. Servile work is not simply any work. We are not Jews who even consider turning on the oven to be “work” on the Sabbath and therefore cook meals ahead of time. We do not define leisure activities as “work”. Even actual work can be done on Sundays-- feeding livestock, working in a store if you have no control over your schedule, police, fire, etc.
So, my question back to you is why do you think that putting up Christmas decorations is “work”, and particularly why do you think it would be work prohibited on Sunday? How much have you read in the Catechism on this topic?