I have something similar. Spring/fall glass, roof with paper, rough-hewn timber, battens/insulation, plastic, and interior paneling. Underfloor heating in the slab, but not connected. "Exhibition carpet squares" on the floor.
The paneling on the ceiling and walls is made of MDF, which I painted myself with interior paint. Since the construction in 2016, I haven't had any mold/growth on the paint. However, there's a little on the aluminum frames, which can be removed with a damp cloth during spring cleaning. Also a little on the floor right by the aluminum tracks.
I made the consideration that exterior paint can smell and become soft if it's in a warm indoor area, which it does in the summer when you want to sit there. I chose not to worry about the interior paint being damaged during the winter, and so far, I am satisfied with that choice. I don't think I tried to find out what the right type of paint might have been.