I am working on this same kit myself, but I am building the Falklands war version.
This kit really is of the new standard for Airfix, the fit is excellent. However, I have heard the kit decals leave a lot to be desired.
I am planning on modeling mine wheels up and in flight with the bomb bay open. I also intend to leave the right front door open. I know Orion crews open doors in flight for a few different reasons, so I am guessing the same of Nimrod crews. I built a little bit of an interior to be visible behind the cockpit, including a closet for the lav. Not sure what else is up in that section, because interior shots of Nimrods seem to be hard to come by.