Thanks.
"ultimate HP experience", this is because most harry potter fans or just games fan will agree that movie games are normally rushed and not very long. This makes me want to make a game that isn't limited to what is in the movie, and that isn't as long as the movie is.

I agree that "travel to all places in the book" may be a bit of a high standard, although i am planning on making cut scenes for the game for non-fans can understand the story, this way i will have most of the locations from the books made just for the cut scenes, so i will most likely just make it so the player can walk around them.

"all characters of the movie and books plus your own", yes this will take a while, but most of the students will just be made from one mesh with different skins and a few alterations. The only characters that will have to be made specially are the main one's.

Yes i do agree about the time plan etc. and i am planning on doing that, once i have planned out the whole of the first game i will make a time plan and make myself stick to it, then i will start modeling the basic levels and try and get an alpha together. I will most likely make it a public alpha for fans to play and comment on what should be improved.

To be honest the only bit i am worried about is the fact that i am not a experienced lite-c coder, and that i am not the most experienced modeler. I believe Hogwarts and quidditch mini-game will take the longest to make.