So a little bit of backstory here.
My groups Rogue Trader was recently revealed to have psychic powers for reasons of plot. After mulling it over and taking the counsel of an NPC cousin of his who is an Inquisitor (and also a psyker). She advised him to travel to Terra either in his own ship or wait around for a black ship to make a circuit. Now based on her own experiences with the black ship's he advised him that since he is essentially turning himself in and has a ship at his disposal he go himself. He had originally planned on taking one of the fleets minor vessels and heading out and playing another character for a bit. However having mulled it over in character and out of character with the party they've decided to take their flagship (a light cruiser) and head to Terra. Now I need brain storming help just to pitch some ideas and see what sticks. I see this as kind of an epic oddessy and hope to play it that way.
What sort of preperations will they need to make before leaving. - For starters the tthought occurs to me that they will need provisions for a long journey, and then will need to tie up any loose ends on their local business. Lastly they will need to secure documents and backing. While the Warrant theoretically allows free travel in the imperium Segemntum Solar especially Sol is a whole other ballgame. I figure at the very least they will want to get powerful people to sign off on their journey. Cardinal's sector and segmentum governors, that sort of thing.
What sort of route will they need to take. Maybe it's just my personal image of 40k but I see intersegmentum traffic as kidn of rare so theere will likely be only a few plotted warp routes. Deviating from these risks great trouble and problems.
How can they make money along the way. The most obvious idea i had was passengers, powerful and wealthy pilgrims interested in making the journey.
What sort of difficulties might they have. - Really this is a place for all kind of long voyage fun, pyrates, space hulks, any of that sort of thing. Jumpy imperial patrols and the like can be fun too.