Where to park at motorway services ?

Just planning my route from Worcester to Grafham water. Corley Services on the M6 looks like a possible place to stop en route, to kill time until the 12:00am arrival, check that the wheels haven't come off etc.

Using Google Earth and Streetview, Corley looks like one of those places where caravanners are expected to slum it among the HGVs. However, on Streetview I can clearly see several large panel vans, a motorhome, and a mini bus towing a trailer, all parked in the 'cars only' area, which is where I'd prefer to park.

What are the possible consequences if I ignore the signage and park in the car park ? I'm wondering if they'd use the ANPR to send me bill some weeks later, does this seem likely ? Anyone have experience of this ?