Neither Hello First Aid or the HSE can tell you what provision you should make for first aid. You, as an employer, are best placed to understand the exact nature of your workplace and decide what you need to provide.
First aid provision must be ‘adequate and appropriate in the circumstances’. This means that you must provide sufficient first aid equipment (first aid kit), facilities and personnel at all times.
In order to decide what provision you need to make you should undertake a first-aid needs assessment. This assessment should consider the circumstances of your workplace, workforce and the hazards and risks that may be present. The findings will help you decide what first-aid arrangements you need to put in place.
More information can be found here …. https://www.hse.gov.uk/firstaid/needs-assessment.htm