Prior to training as a clinical psychologist, Zillah worked in a number of different hospitals for people with intellectual disabilities or mental health problems, including as a volunteer support worker, psychiatric nursing assistant and assistant psychologist. Zillah completed her BSc in Psychology in 1981 at the University of Birmingham and in 1984 she gained her MSc in Clinical Psychology at the University of Surrey. She then undertook two years training in family therapy resulting in a Certificate in Family Therapy from Birkbeck College and the Institute of Family Therapy. In 2004 she gained her doctorate in clinical psychology from Canterbury Christ Church University College. The specialist focus of her doctorate was autistic spectrum disorders. In 1989 Zillah became a chartered clinical psychologist with the British Psychological Society and from June 2011 she has been a registered clinical psychologist with the Health and Care Professions Council. Since qualifying, Zillah has worked in a range of roles in the NHS in services for children (CAMHS and paediatrics) and individuals with intellectual disabilities including community and inpatient settings. She has also worked in the voluntary sector in a specialist service for individuals on the autistic spectrum.

Her current role is in a specialist inpatient service for individuals with intellectual disabilities and mental health problems.