If you are in a workplace then your employer has a legal responsibility to ensure that first aid provision is available under the Health and Safety at Work Act (1974) and in particular the First Aid Regulations (1981) which ‘require employers to provide adequate and appropriate equipment, facilities and personnel to ensure their employees receive immediate attention if they are injured or taken ill at work’.

https://www.hse.gov.uk/firstaid/legislation.htm

‘Teachers and other staff working with pupils and students are expected to use their best endeavours at all times, particularly in emergencies, to secure the welfare of the pupils and students in education in the same way that parents might be expected to act towards their children’. 

https://www.gov.uk/government/publications/first-aid-in-schools/first-aid-in-schools-early-years-and-further-education

‘At least one person who has a current paediatric first aid (PFA) certificate must be on the premises and available at all times when children are present and must accompany children on outings’.

https://www.gov.uk/government/publications/early-years-foundation-stage-framework–2