https://www.gov.uk/government/publications/regulatory-article-ra-3224-flight-information-services-fis-outside-controlled-airspace-cas
Regulatory Article (RA) 3224: UK flight information services and north atlantic treaty organization...
RA covering FIS which can be provided under differing conditions to maintain a safe and expeditious flow of traffic.
flight information services
https://www.gov.uk/government/consultations/uk-flight-information-services-notice-of-proposed-amendment
UK flight information services: notice of proposed amendment - GOV.UK
Seeking views on proposed amendments to 'UK flight information services (CAP 774)' following a CAA and Military Aviation Authority review.
flight information servicesproposed amendmentuknotice