Have you looked at Ordnance Survey or ONSPD data? e.g. https://www.ordnancesurvey.co.uk/business-government/products/code-point-open https://www.ordnancesurvey.

Have you looked at Ordnance Survey or ONSPD data? e.g. https://www.ordnancesurvey.co.uk/business-government/products/code-point-open https://www.ordnancesurvey.co.uk/business-government/product... There's also a service called MapIt which wraps it in an API you can host, and even provides a public instance for limited uses: https://mapit.mysociety.org/ https://mapit.mysociety.org/