Art psychotherapy is a protected profession and requires a degree at Master’s level in Art Psychotherapy from an accredited university course. When qualified, an art therapist must register with the Health and Care Professions Council (HCPC) in order to professionally practise. Both Karen Vost and Lydia Hunt are fully registered with the HCPC and protected by Psychologists Protection Society insurance (PPS). Any work undertaken by them is legally required to meet the standards and ethics set out by the HCPC.
You can check for Karen Vost and Lydia Hunt on the HCPC registry here: https://www.hcpc-uk.org/check-the-register/.
You can read the HCPC standards of conduct, performance and ethics here: https://www.hcpc-uk.org/standards/standards-of-conduct-performance-and-ethics/.