just came across this government webpage for landowners restricting access and when they can not restrict access
https://www.gov.uk/guidance/open-access-land-and-the-coastal-margin-how-to-restrict-public-access
28-day restrictions
You can exclude or restrict public access rights for up to 28 days per calendar year except for land in the coastal margin. On tenanted land, the farm tenant has the 28-day restrictions allowance, not the land owner.
You can’t use these restrictions on:
- bank holidays, Christmas Day or Good Friday
- Saturdays between 1 June and 11 August
- Sundays between 1 June and 30 September
- more than 4 weekend days in any calendar year
https://www.gov.uk/guidance/open-access-land-and-the-coastal-margin-how-to-restrict-public-access