I believ Satnav is factory fit and can not be done as later option. If you really want it suggest you get back in touch with dealer pronto to see iuf order cna be amended. However there is some uncertainty at present about how you update the sat nav maps so might want to check this out with dealer before you spend £400 pound - portable options are more user friendly in my opinion and a lot cheaper !
You might be ok if its a build from a factory and not coming from dealer stock. Give them a ring to see if you can change your order. But as others have said, a £100 Tom Tom would be as good, just doesn't have the fullyintegratedfeeling.
Within a week of getting my Allure 1.6 eHDI 92 with Sat Nav, I ordered a new version of TomTom because QVC had an offer including lifetime maps update.
I do still use the 208 Sat Nav but it isn't as easy to set the destination, and it doesn't do postcodes. Also the Lady gets very upset if you disobey her and seems unable to adapt to the road that you insist on following; my TomTom gives in to my wishes much more easily.
Someone on here suggested that the Peugeot Sat Nav would be updated with postcodes, but I don't know how to get updates or how to install them