Your first stop on mainland Europe should be a customs airport. I would recommend Texel (EHTX) which has ~1100m well-maintained grass. Very friendly, good restaurant, customs available (check AIP and website for customs availability; best to call in advance anyway).
If you intend to follow the coast all the way, beware of the restricted zone near Vlieland, EH-R4. If it's active (weekdays, but check NOTAMs for weekend activations as well) it's better to remain south of the EHKD CTR, then cross from Den Oever to Kornwerderzand and proceed to the coast again by way of Ameland (EHAL).
A significant portion of the Dutch leg will be underneath the Schiphol TMA, which starts at 1500' (class A). But that part of the country is mostly below sealevel so 1000' AMSL is considered normal & safe.
Further down the route, a lot of the German islands actually have airfields as well. Hopping from island to island is an extremely scenic route to get to Denmark.