Steve Coogan's comic creation is expected to arrive on the big screen in 2013, following a confirmation of shooting later this year, and Iannucci insisted that the film would "preserve the intimacy" of the classic Partridge TV series.
"The Partridge movie starts at North Norfolk Digital. But it would be a terrible film if it was just a 90-minute version of his show on North Norfolk Digital," the exec producer told DS.
"But it's not Alan goes to America or Alan goes to space or anything like that. We've tried to preserve the intimacy and the localism of it.
"But at the same time we've tried to give it a story that justifies it going on the big screen."
Joking about how the hapless Norfolk DJ will go down with US moviegoers, he said: "I'm told there is a place called Norfolk in America. I think what Norwich wants more than anything else is lots and lots of American tourists flocking up.
"If we can do that for Norwich our mission will be over."
When asked where the Partridge character is right now in his career, Iannucci said: "I think he's still frustrated that he hasn't been asked onto something like I'm A Celebrity. He could be one of these people who were considered naff 10 years ago and have been reacclimatised to a younger audience by being on something like that. He's not had that call."
Father Ted's Declan Lowney is directing the movie.
Partridge, who was created by Coogan, Iannucci, Stewart Lee and Richard Herring in the early '90s for radio, is making a TV comeback later this month on Sky.
Sky Atlantic's first one-off Partridge special - Alan Partridge: Welcome to the Places of My Life - airs on Monday, June 25.
