Hi there,
Amy here, a current MSc Children's Psychological Disorders student at Cardiff University!
Having just graduated from my Psychology undergraduate, I think having an A-Level in Biology was relatively useful in understanding some of the neuropsychological topics, such as brain structures and the nervous system. However, lecturers are aware that not everyone has a biological background, therefore they usually tend to re-explain these concepts just to make sure everyone is on an even playing field (in my personal experience at Cardiff anyway)!
However, if you have concerns regarding admissions, I would definitely recommend contacting the admissions team at any universities you're thinking of applying to 🥰
-Amy, Cardiff University Student Rep