Are you looking for regular Styrofoam panels or extruded polystyrene(XPS) for insulation or the EVG panels that you use cement render on instead of hollow block?
I do not know where to find Styrofoam panels and also interested in sourcing XPS panels for a different project. I used EVG panels for my house build and think they are a great product. More expensive material wise than the cheap block here but you save a ton of money on labor so overall you save money and get walls that have both acoustic and insulation value.
If EVG panels I can give you info/installation advice or you can search the forum, I made many posts on it. If the other panels I'm sure someone will chime in with the info you are looking for.
Shawn