I have sent the chap who owns the land, Tony, an email asking. The place we are heading to is a working farm as well as an equestrian centre. I know they have a horse event the same weekend as we are there but I am not sure how big an event it is. If it is only a small one then we might be ok to use the area the horse transporters normally park on.
Will post up the answer when I get it.
Ian