try typing into google "cours francais université belgique"

If you are non EU, unless you have 5+ years permanent residence or EU family members living with you, you must normally live in the country which has issued a work permit. As you have been given a Dutch work permit, it suggests you cannot live in Belgium. If you were work permit free, that would indicate you are 5+ year permanent resident of the EU / have EU family members. Be thankful you have a job. Be thankful you have friends and relatives. Be thankful you can feed yourself. Go and live in the Netherlands as required by your work permit and respect the country's laws which is hosting you.

You need to get your qualifications recognized. If your partner is Belgian, he/she should have the ability to look this up on the internet for you as to the procedure. It could take many months. You also need to be able to speak Dutch to a decent level. Your only alternative is the 3 international schools in Antwerpen.

Sorry here is the link I forgot for the basisscholen in Leuven. You'll find English speaking families with children in schools in central Leuven inside the ring and also in schools in the south outside the ring near the KU Leuven Heverlee campus. But as you're at KU Leuven, why not ask the academics there where their children go? http://batchgeo.com/map/85cf95329b52fff40dbc0f036130dc47 You'll have to do your own research if you're after SECONDARY school students. http://www.ond.vlaanderen.be/onderwijsaanbod/lijst.asp?hs=311 Facebook is the best way to find people, there are expat groups on there of English speakers in Belgium.

Only 6 out of the network of 15 international semi-public primaries are in Zuid and Noord Holland, the other 9 are in the other regions of the Netherlands. There are no schools like this in Belgium, schools are either public and in French / Dutch / German, or private and in any language the school chooses to teach in, with fees starting at 6k per year to 35k per year. The private schools in Belgium tend to be expat enclaves where a large percentage of the children never learn the language of the area.