If you take the canals you can just enter Germany
down and follow
the canals and rivers.
If needed, I can give you all directions to the Med, it 'll take a bit of time only and during the winter the French are working on the inland waterways so it might be possible that you will have some delay at ..... canals. The big ones will be open anyhow but there are some smaller ones that you have to pass.
If you sail your own boat, neither in Holland
nor in France
they will ask for your ICC
as long as your boat is below certain limits: < 15 meters and no higher speed than 20 km/h under power. Framnce might be different but anyhow nobody will ask you. Once in the Med, nobody is interested as long as the boat is your own.
Make sure that your boat is seaworthy
by all means.
The German Bight is no laughing stock if the weather
turns nasty, neither is the Elbe apparoach - those water
are pretty unforgiving.
Insurance is mandatory everywhere. The boat not so much but personal liability is. Pantaenius is a good address. They are internationally recognised and handle anything that floats.