Are you the victim, or their parent or close relative? You can apply to join the Victim Contact Scheme which entitles you to be told if the offender has moved to an open prison, be told if the offender is being considered for release, or ask for additional conditions to be added to an offender’s licence, for example stopping the offender coming near your home.
Otherwise no, there is no law or mechanism allowing for ordinary members of the public to locate an offender or ex offender.