An officer may phone and request that you attend the police station in order to be arrested and charged.
Ask for time to consult a lawyer before coming in. Usually the police will agree.
You do not generally want to turn yourself in on a Friday afternoon or a holiday and be held over in custody until Monday for a bail hearing.
If you do not attend the officer may obtain a warrant for your arrest, or may arrest you directly without warrant if he believes you were committing a crime.