Back in the day we used the Ordnance Survey maps - the ones with the orange covers. https://shop.ordnancesurvey.co.uk/map-ranges/os-paper-map-ranges/explorer-maps/
From the interwebs: “UK Ordnance Survey maps display a detailed representation of the British landscape, including roads, buildings, rivers, natural features, and other geographical points of interest, using a system of symbols and colors to denote different elements, making it easy to navigate and understand the terrain with a specific focus on accurate location data across Great Britain.”
And from the OS website: “The essential map range for those who like to explore and discover. Our famous orange Explorers are the only maps of Great Britain to display footpaths, car parks, contour lines, campsites, pubs, and more. Always know your location whether walking, running, cycling, or horse riding – every map comes with a free digital download for your devices to use while out.”
There is soooooo much detail, however (there is a LOT of stuff in the UK to cram in) that I don’t think there’s a single map for the entire UK. They are regional.