A headcam/bodycam is a 'hands-free' video recording (and possibly audio recording) device that is worn about the person in order to create a visual record from that person's point of view. This device will usually produce a video feed either to be viewed live by another person in another location, or to be somehow captured and stored for later review.
Individuals who view footage recorded by headcams/bodycams are likely to fall within the definition of public space surveillance (CCTV) activity. If you are employed to use CCTV equipment to monitor the activities of a member of the public in a public or private space, other than for the purposes of protecting property or identifying a trespasser (e.g. if you use CCTV to guard against outbreaks of disorder), and this activity is carried out in connection with any contract for the supply of services, then you will require a Public Space Surveillance (CCTV) licence.*
If you simply wear a headcam or bodycam but do not watch or review any of the footage from that device, the SIA takes the view that this does not fall within the public space surveillance (CCTV) definition. You would therefore not require a Public Space Surveillance (CCTV) licence.
When dealing with matters relating to public space surveillance (CCTV), the General Data Protection Regulation (GDPR) and the Data Protection Act 2018 (and the seven data protection principles that underpin the regulation) must be taken into consideration. Public space surveillance (CCTV) captures information about individuals, and information held by organisations that relates to individuals is covered by the GDPR and Data Protection Act 2018. Most organisations that process personal data are required to register as a data controller with the Information Commissioner's Office.
*However, if you view footage recorded by headcams/bodycams solely for the purpose of protecting property or identifying a trespasser, then a Security Guard or Door Supervisor licence would be sufficient. Due to licence integration, a Public Space Surveillance (CCTV) licence would also cover you for this activity.