Michael Leddy, over at Orange Crate Art, has some great tips for students on how to approach a professor. Being US-based, there will be differences for UK students. Don’t call someone a professor unless they really are a professor — otherwise they’ll think you’re taking the piss.
Some of my best college memories are of talking with my professors in their offices. I was a shy kid (still am!), and I treasured the chance to ask questions and try out ideas during office hours. Sitting with my coat and books piled on the floor, I found my way into the possibilities of genuine intellectual dialogue. You can do that too.