You will need to download MiraScript from gpsunderground (you may need to search their site for a link) once you have used this program as per the instructions on their website, this will enable you to install any updates without the need for any activation codes.
As for the 7 digit postcodes, you will need to update the maps first I'm afraid. These are also available on gpsunderground. I downloaded the maps and MiraScript from their site, I am no Computer genius, but just followed all the instructions, and everything worked perfectly.
I have just installed the latest firmware from their site (2.86) and Tianorth sent me a zip file with the latest risk areas(speed cameras).
I really didn't like the built in sat nav when I got the car, but now it's all updated, it's brilliant.
Good luck with your efforts, and there are always people on here who can offer advice if you get stuck :helpme: