hi there
first of all, welcome to Belgium.
Sorry to hear of the attitude of one of the head teachers towards learning another language and towards your son, I hope his views are minority ones. Children who arrive late into the Flemish system or go into Flemish primary from a French one have to take a special language test in 3rd kleuter, I asked around about this recently, the test does not in fact sound too hard at all, it is mainly based on comprehension and full fluency is not expected. Am I right that your son has started 3rd kleuter now? There is a chance he'll pass the test, well if not, then he stays back for another year to perfect his Flemish, but to put him immediately into 2nd kleuter seems a rather defeatist attitude.
The mumsnet group is going out on Friday, you should join them - it's centre of Brussels, send longtime or portofino a private message.
As for health insurance, your husband will be paying social security and this covers the "compulsory" insurance you will get from a mutuelle. Then if you are working, you also have to join a "complementary" package at a mutuelle, I find the name confusing as it is also compulsory if you are working!!!! We pay 6.50 per month per adult with Euromut, same package with Partenamut is 7 euro so expect similar pricing with all the mutuelles.
Which mutuelle to join? Well for me I found it important to have an office nearby, so I ruled out Partenamut and Symbio straightaway as they don't have offices near my. I have indeed found it useful having the office nearby. But it is not the only consideration. The complementary packages are pretty similar between mutuelles. A bonus to a mutuelle membership when you have children is the reimbursements you can claim for sports camps and club memberships. In retrospect, if I had chosen a mutuelle for this aspect, I would have gone I think for Symbio or Partenamut, off the top of my head these mutuelles give more money back for sports camps! Some mutuelles run their own sports camps too, Mutuelle Chretienne is especially appealing in this respect. But it is a small point, it might not matter too much.
Many mutuelles now have some of their information in English - certainly Symbio, Euromut, Partenamut do.
It seems pretty much all mutuelles are quite efficient at refunding quickly.
All mutuelles offer top-up insurances such as hospitalisation and dental. I'm the only person in our house with hospitalisation insurance (through work for free) and it is a risk I take that the rest of the family are not covered. It's up to you to decide the risk and also I would compare costs. You can also buy hospitalisation insurance from other insurance companies, not just from a mutuelle, eg DKV and Ethias.
The child benefit is applied for through your husband's work and he should get that sorted ASAP. It will be paid by whoever the mutuelle is of the employer - for me it is Partenamut, but I am not a member, only my employer is. Yes that is confusing, nothing to do with personal mutuelle membership, you cannot choose who pays the child benefit. For one child, it is not much, about 100 euro a month, but still worth claiming. You can claim from the day your husband started work in Belgium, not from the time your son arrived - if you have claimed already in Greece, then that is deducted from the Belgian claim and Belgium pays Greece back - that is dealt with by the child benefit provider, don't worry about that aspect if relevant.
I have no idea if you get more child benefit if a parent is unemployed, I suspect not. However, your husband will claim tax relief on his salary as you are unemployed, maybe that is what your relatives mean, it means your husband will pay less tax, he also gets an allowance for his son. The entitlement to these allowances should be shown on his salary payslip every month - one mine it mentions "4 children at charge" and I receive the tax relief for them.
You know you can officially register as unemployed? It will give you access to free training courses, including 60 hours of free language tuition. In Brussels the organisation is ACTIRIS, can't remember the name of the organisation in Flanders. For the free language courses, you get a booklet of language course providers. You might find GLTT is one of these providers, so you might find that you can do 60 hours of Dutch tuition with GLTT for free, but you need to apply for this entitlement.