Works van or car ?????

Hi everybody

Been camping for 15yrs+ ,kids off our hands now so just brought our self’s a newish van with fix bed (bliss) , my question is ? I’m I right in thinking that vans or commercial vehicles of any kind , plain or sign written are not allowed on any sites ?  .I have a Mondeo that I tow with but also have use of a works van.

Regards Shaun