It depends how much you want to cram in, where you want to go.
IF:
- from North to south; Ferry Harwich to Esbjerg, couple of days on the Beach. Legoland.
- the way down means Hamburg - Hannover - Kassel - Frankfurt - Heilbronn. Doable in one long trip or multiple smaller ones.
- Tour would need to be on a weekday (I have to check if they're actually working!)
- back up via the 'ring to Calais means around 1200miles in a week - ten days.
If you don't feel the need to do the 'ring, then you're in a good position for the Alps, Switzerland, Italy (Basel is around 3 hours from Heilbronn). You could also easily dive over to Prague.
that's some of the ideas right now; if I manage to make it, I'll probably be on the beach in Sweden for a few days beforehand, and after the factory trip straight back up as I have to be on a ferry latest 080809.
Bret