It's just a normal apartment, in a town between Pirriwee and North Sydney, complete with dingy gray carpeting and a poky little kitchen.
This is part of Celeste's escape plan; she plans to leave the next time that Perry hits her.
Or, at least, she plans to tell her therapist that she has a plan for the next time Perry hits her. She wants to impress her therapist with her preparedness.
She feels a pang of self-loathing about this—that she wants to get the equivalent of good grades from her counselor.
She loathes the idea of moving into this tiny apartment, she thinks. She'll be far away from her friends in Pirriwee, she'll have to cook in a tiny kitchen, she'll never see Perry's family again, she'll lose the magic aspect of their life, she'll never be as attracted to anyone as she is to Perry.
Although, she has to admit to herself that there's something unnerving about the sheer amount of wealth that Perry has. They are so rich.
Maybe, she thinks to herself, the violence is a way of balancing out how perfect the rest of their life is…or at least how perfect it looks.