caravan sites accept transit vans ?

Hi,

we are newbies, we have been talking for a long time now about becoming a caravan owner, but our car would not pull the size we are looking at purchasing,  we have a transit van which we go on most UK holidays as we like taking bbqs, bikes, our dogs, etc, we are now considering not upgrading our car, but fitting a towbar on the transit and using this to pull the caravan, now our biggest question is, do sites restrict you taking a transit van on to site ? We ask this, as we went to a site and hired a caravan which was on site and as we take our bikes etc, arrived on site to be told we could not grin our van in site!!! Thanks in advance.