Not sure of schools in the Netherlands, but I would budget far more than one year to learn the language at an academic level. Within school districts, it is generally accepted that students learning English will get to an academic level of reading in 5-7 YEARS with strong steady work and progress.
We have one person in our class who came to the US six years ago now, but they still struggle with instructors not being able to understand their accent and issues related to more technical terms.
Are you guys planning on moving?
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The ultimate measure of a man is not where he stands in moments of comfort but where he stands at times of challenge and controversy - MLKJ