I didn't know this thread existed, otherwise my last thread on this subject would have been appended to this one
I have some indirect contact with Herts Police, but I don't think it would make it any easier than getting in touch through an official channel, would it?
Something I think could be implemented quickly would be for the McDonalds parking attendants to actively keep an eye out (hire staff if required) to intercept these people before they enter the BP and/or keep an eye on people parking to eat/buy food and discouraging them from doing so, or perhaps even telling them to not to. I did suggest this to the franchise, but I didn't get a reply.
I've given up using that BP, life's too short. If something isn't done about it someone is going to get either seriously injured or killed on that roundabout, I've seen HGVs going some speed narrowly miss the cars lined up.