Five islands to the north of the Netherlands, collectively called the Waddeneilanden. Two of them have airfields, both very nice destinations: Texel (EHTX) and Ameland (EHAL).
In the southwest of the Netherlands are the former islands (now connected by dikes and bridges) of Zeeland. One airfield, near Goes, called Midden Zeeland (EHMZ).
All three are grass strips. Texel and Midden Zeeland are Airports of Entry so you can route direct from the UK. (EHMZ requires 1hr PN for customs.)