I want to cut all contact with my family can they involve the police?

I want to cut off all contact with my family and immediate relatives. I'm obviously not a minor and once I move out I can sustain myself independently without any problems. Due to many years of toxic and narcissistic behaviours from my family I am no longer willing to be associated with them any longer. They are both job holders and not senior citizens.So I think I'm right to assume they can't ask for the senior citizen maintenance claim right? I'm planning on going out after informing them through a letter and not confront them face to face to not create a scene and increase my own problems. Can my parents file for a missing diary to try and come find me? What can I do to prevent them from doing so? I'll ofcourse be changing my phone number and I also won't be informing anyone about my new address after I move out of my parents house. I also don't want my parents to bother my current partner as she won't be moving in with me till next year and still stays with her parents.Is there something I can do about that as well?