OK certain conditions within the game have to be met to start off with the tanker chapter instead of the plant chapter - this is how to do it...
Get to the main menu
New game
1st time or whatever is available
either: ive played previous games multiple times
ive completed the previous game but action is not me
i havent completed previous game but i watched it all
This will start you off with the tanker chapter unless you choose a different option which gives you raiden. Personally i think the tanker chapter is a little too short...
Anyways problem solved - thanks for the help guys...