This is a problem I've been wanting to address. Different countries have different connections and it's hard for someone in the US to say exactly what you might need. I have the vision of putting together a guide for different areas of the world. I guess I should get started.......
Let's start with you posting a couple of pics of the tank and regulator fittings you are working with in Belgium and we will go from there.
No such thing as hopeless.....difficult maybe.....not hopeless.