So with the jobs sights genuinely not rosy one can still become independent and work as a freelancer.
Also, you can make additional building plans, so that you can build even small houses and if an architect says that he does the interior planning, I only say: no wonder nothing is matched and the blindest corners arise if you look at some “buildings,” it can be appalling. Have unfortunately not yet met an architect who has dealt with the interior design, so do not let you tell.
You will have a basic knowledge of design, design, light planning, building physics, furniture construction, ergonomics, architectural theory, etc. Then there are projects at the FH, where you can apply your knowledge. You can choose for different directions, as written by Sarah.
Good interior designers with new ideas are continually asked both math and physics you will only need conditionally when it comes to the understanding of building science and some architectural theory.
More important is a great knowledge of spaces, colors, and connections.
Ask for the appropriate FHs that are suitable for you, because many have recently changed the regulations and added further jobs to the list, which will save you a long internship (which you can do in the first semester breaks).
Look in the large cities for internships, best personal with new CV, etc. appear and ask, makes a good impression. I would snap all the big arch offices, but the little gilded are mostly synonymous.
General: Some FHs do not want any maps, you can find on their homepages. Information is also with the study guide from the employment office … there is where you can read what is left, etc.