Just seen this posted on Facebook that BP council are opening more car parks to MHs for overnight, sleeping is allowed but no camping such as awnings, chairs and so on.
https://www.blackpool.gov.uk/Residents/Parking-roads-and-transport/Parking/Motor-home-parking.aspx
https://www.blackpool.gov.uk/Residents/Parking-roads-and-transport/Parking/Motor-home-parking.aspx