I usually import the real FT foam from the US. In Germany, Graupner did the distribution for FT products, but they are out of business now. You can get a few kits from Lindinger or other RC shops, but they are super expensive because of the shipping from the US. If you want to use Foamboard, the FT stuff is the only option, because its much lighter and easier to work with than other options. I've tried Gerstaerker Foamboard, and it sucked. I prefer brown FT over white FT. Foamboard itself is a great building material because its relatively stiff. Its downsides are warping and paper seperating, which makes your planes last not so long. You can also try depron, which is light, but brittle and needs carbon reinforcement to make it stiffer. Than theres EPP, which is very crash resistant, but hard to cut. You need a hot wire to cut it. Also, its surface structure is pretty shitty and creates lots of turbulent flow, which makes your plane easy to fly at slow speeds, but performance suffers.
Im personally moving away from Foamboard, because I dont get planes that last forever out of it. My new material of choice is called Flexi Foam, and its almost unbreakable, but needs carbon reinforcement. Its not easy to cut, but offers great crash resistance. However, I would not recommend it if you don't have access to a Laser cutter or CNC mill.
My recommendation for you would be to look for FT foamboard or FT kits or use depron.
For the airframe, as others said, the goblin is no ideal beginner plane. A good beginner plane has light wing loading, making it slow, a distinctive shape making orientation easy, and the motor and prop in the back which puts the dangerous and expensive parts in a safe spot. Good beginner planes are: FT Explorer or AirC Pirates (also a German) Trainer, FT Bronco with single motor, FT speedster biplane mod, or my Dornier Libelle or Opel Rak 1.