Sectioning Off Part of House for Student Accom

I live in double story house in Melbs Eastern suburbs

Proximity to Unis etc , in terms of distance / transport is quite good

There is just myself & partner at the house which is double story

So I am thinking of modifying the upstairs to contain 3 or 4 rooms with ensuite / study areas
for students ; doing it nicely

As the house is double story , the logical way to proceed would be for top floor to be just for students / bottom floor
our area

The logical way to proceed would be to also set up a small kitchen / open TV type area upstairs for the students
, even to have outside stair case if possible (thinking that would mean planning permit)

I have heard somewhere that councils don't like allowing people to do this kind of stuff , 2nd kitchen , 2nd "living type area" so people disguise it under calling it a "craft room" etc

Any advice on this or how to proceed , just all in the conceptual stage atm

I only need a planning permit (& I know this is complex) if I change the "structural envelope" of the building or outside appearance

Perhaps a reasonable idea might be to a "discreet stairway" which is still inside the house ; meaning the studs don't have to come in & "announce themselves" every time they come & go