Upgrading a newer map disk?

I have just purchased a newer, (more modern map disk), (old one was 2003), can I just change the disk in the unit, or do I have to run a system disk in the unit first, if you do have to run a system disk, can anybody tell me where to get one, as I do not have one with the car, (which was purchased 2nd hand), my car is a 607, on an 04 plate.
The system installed, I think was factory installed, and runs a 'NAVTEC' disk, I have contacted 'Navtec' and they just said,
"we only supply the map data disks, please contact Peugeot etc."
and trying to do that, as some of you out there will know, is almost impossible, so, hence the question.
I have not yet received the new data disk so I have not yet tried to 'put it in the unit, to see if it works', PLEASE if there is anyone who can help me I would be most greatfull , thanking you in anticipation, I remain,
Glenn