Health Provision in the UK
The British NHS system provides free initial emergency care to all visitors to the UK.
However, any prescriptions (medications) and non-emergency care will need to be paid for, including if your child is admitted to hospital following emergency care in an Accident and Emergency Department.
Further information can be found at:
http://www.nhs.uk/NHSEngland/AboutNHSservices/uk-visitors/Pages/accessing-nhs-services.aspx