UK Radon
https://www.ukradon.org
Radon Risk Report
https://www.ukradon.org/services/address_search
GeoReports service https://shop.bgs.ac.uk/Shop/Department/GeoReports
Building Research Establishment website
https://www.bre.co.uk/radon
PHE list of laboratories offering long-term radon detectors https://www.ukradon.org/cms/assets/gfx/content/resource_3462cs9edda0fd4d.pdf
UK Health Security Agency https://www.gov.uk/government/organisations/uk-health-security-agency
Radon solution sheets
https://www.bre.co.uk/page.jsp?id=3134
These sheets were prepared by BRE for the Department for Environment, Food and Rural affairs in 2003. They remain useful for installers but you are advised to also consider the more recently published guidance contained in:
BRE Good Building Guide GRG 37 Part 1 Radon solutions in homes: improving underfloor ventilation
BRE Good Building Guide GRG 37 Part 2 Radon solutions in homes: Positive house ventilation
BRE Good Building Guide GRG 37 Part 3 Radon solutions in homes: radon sump systems
Good Build Guides
https://www.ukradon.org/resources
Approved document C: Radon
www.gov.uk/government/publications/site-preparation-and-resistance-to-contaminates-and-moisture-approved-document-c