Sounds like a very nice ride, but it's a bit early for northern europe. If the weather is anything like last spring you will get wet and cold.
My wife and I will be flying into Milan than cycle through Tuscani to Rome. From there well follow the Appian way to Brindisi then catch the ferry to northern Greece and spend another 2 weeks cycling towards Athens.
If you cycle through Maastricht in the south of Holland and have some questions let me know I'd be happy to help.