In reply to Nigel R Lewis:
> 1. Are the pre-loaded Topo maps any good or will I need to use a proper hand held map as well?
They're not that good. Consider openmtbmap... coverage is not universal or perfect, but it is often very good. More importantly, it is free.
A paper map is often a good idea anyway. Electronics can fail, and scrolling around on a tiny screen gets tedious fast.
> 2. Can I add the Euro topo maps to a 600 at a later stage?
Yes.