Hi Ian,
I'm not sure if yours will be the same as mine but they're both 64 plates. Check the handbook under the 'Touch Screen' section (p64 in mine) and you should find 'Home Menu Shortcuts' under the 'System Settings' section.
That gives, on mine at least, the choice of adding two shortcuts to the main screen. 'Take me Home' is one of mine. You might need to deselect the one you already showing and, of course, choose a 'Home' location for the SatNav to take you back to!
Hope that helps ...
Rich.