Planning applications in the UK are publicly available and many have architectural drawings/site plans attached with varying degrees of detail.

There are millions of applications and each local authority has a different database so it may take a bit of digging to find what you are searching for.

Application example - https://publicaccess.tewkesbury.gov.uk/online-applications/a...

Drawings example - https://publicaccess.tewkesbury.gov.uk/online-applications/f...