Here is small code snippet you can copy to your child theme functions.php to change the postal code checking to check only the prefix instead of whole postal code.

This is useful for locations like UK where postal codes are too many..

function change_to_prefix_postal_checking( $bool ) {
     return true;
 }
 add_filter( 'woofood_check_postal_prefixes', 'change_to_prefix_postal_checking', 10, 1 );