After seeing John's inspiration from the Gnomon DVD on digital painting I thought I should find out more from Alan about them. He then recommended me this DVD:
It was SO useful! I've mentioned before about how bad I am at perspective and it's so important to this project that I had to seek out something to help. This DVD was it! It's teaches you everything you need to know about setting up a scene and how to create depth with values, it's just SO good! I can't wait to try it out, I REALLY recommend it!