See

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/900910/Land_Use_in_England__2018_-_Statistical_Release.pdf

Given a population of 77 million each citizen of the UK would have about 0.78 acres of land id shared, but as some is used for communal access that is reduced by just over 8% giving a final allowance of just about 0.7 acres