In reply to Bingers:
Another Yorkshire didn't know here too.
It would not be too bad if the signs were posted far enough in advance to do something about it but I bet they are not.
Last time I went south it was midnight and my wife had been taken in to hospital after collapsing at proms in the park.
With only 1 junction to go I saw a sign saying emission charges apply past this point so I stopped in the services to get some info on what this entails. No signs, leaflets, asked the people working there but they didn't know either if I could take my van in.
Apparently in the south people just learn things like this through osmosis.
I did finally get the info via a crappy data signal and my phone but it was not straight forward.