I came across this really helpful article, follow the link here.
After asking questions I also recieved this helpful comment from Tim Stout:
“You’re right. Page count does differ depending on the project. As you’ve probably noticed in book stores, mainstream comics tend to have 128-256 page graphic novels because they are collections of 4-8 issues of 24-32 pages each. And stand alone graphic novels are typically 150-300+ pages. So, unless you intend to do a 1,000+ page graphic novel, I wouldn’t worry about page count. (If you are planning to do 1,000+, well… I’d recommend trying to split that up into issues or chapters or into a trilogy — easier bites for publishers to swallow.) As for accepting just the script: some do. Some publishers want a completely finished book before they publish while others are willing to take a script — best to ask them individually. And it’ll definitely help to have well-drawn, well-suited visuals to accompany the script. Even if it’s just the first ten pages, or finished character sketches. An image is worth 1,000 words, and when a GRAPHIC NOVEL publisher has to choose between a 200-page script of just text or a 200-page script that has comics accompanying it, of course they will want to read the latter.“