Professional bodies serve a different role to professional regulatory bodies such as the HCPC. They usually govern specific interventions and treatments. It is good practice to be accredited by the body that governs a therapy that you provide, however this is not a legal requirement and many therapists choose not to be accredited.
Some of our services, as a result of national NHS-E policy, require their practitioners to be accredited with certain professional bodies. For example, CBT Therapists working in Adult IAPT services are required to be accredited by the British Association of Behavioural & Cognitive Psychotherapies (BABCP).
If you have a question regarding the requirement for accreditation within your service you should discuss it with your clinical supervisor or service clinical lead.