You do not HAVE to indicate when leaving a roundabout...
http://www.dpi.wa.gov.au/mediaFiles/lic_drivesafe3.pdf
Page 66
"Indicate/signal left, if practicable..."
i remember this coz i was teaching the missus how to drive late last year.
and on Page 72 YOU must give way to all traffic already on the roundabout.
so alot of ya dunno the rule eh.
but yeah indicating helps and i get shitted off by people who dont, and also people who dont give way at the vic park peanut style roundabout!!!
roundabouts r death traps