I also tried looking for the 'Leaky Cauldron' in the first Harry Potter film. However i couldnt find any images on that, so i looked at the environment within Hogwarts, and that dusty, dark feel you get that only happens when there is natural light, such as candle or torches alight.
Continuing on with the lighting theme, i looked at street lighting. The reason behind this was because i havent decided on a specific scene yet, and was tinkering with the idea of something outside.
I like the fact that a little piece of lighting can give you that creepy feeling, that there could be something just beyond the lights rays.