Can anyone explain why the s e plus has a satnav the l&k also has satnav so why does the elegance which is between the two does not . So if thou want it you have to have it as an option

As far as I know, the SE+ was a limited edition option. So you bought an SE, and then paid an extra amount to "upgrade" to + spec. This grants you the Amundsen sat nav amongst other upgrades. The L&K gets sat nav because its top of the range. The Elegance and SE do not get sat nav. 

You could buy an Elegance / SE and retro-fit the sat nav if you wished.