There is a British Standard BS 8599 for first aid kits, it is not a regulatory requirement under the Health and Safety (First-Aid) Regulations 1981 to purchase kits that comply with this standard. Instead the contents of a first aid box is dependent on an employers first aid needs assessment.
This means for employers following a needs assessment the options are:
1. Within your workplace you have access to a first aid kit whose contents complies with BS 8599 and matches your needs assessment;
2. Within your workplace you have access to a first aid kit whose contents matches your needs assessment but does not comply with the requirements of BS 8599.