I would take clutch and throttle cables. Because they are probably specific to your bike. Fit the new ones before you leave and carry the old ones as spares.
I do an annual service at the beginning of the riding season and that is usually enough for my trips.
If your bike has a rear chain you might want to make sure it has plenty of life left in it.
I carry a spare, but it only takes a couple of minutes to change on my bike. Most modern bikes take longer and use the much better x or o ring chains.
Also take a look at your tyres, not only tread depth but check for sidewall damage.
Germany is a good place to ride, the roadside hotels are often not overly priced and food is better value than UK. I usually as for whatever is a local speciality.
make sue you have all your paper work handy in a waterproof bag including credit cards and you will be fine. Generally though I pay cash for everything and use cash machines.
enjoy your trip.