Sydney flight - unaccompanied child

Thanks in advance for any advice... we are sending an 11 year old to
Sydney (from London) on her own, and need flights around June 30th,
returning August 9th...

On a long-haul trip like this, anyone have experience of sending an
unaccompanied minor? Best airlines? Which ones do the 'simplest'
routes?
Never been south of the Equator myself, so would be grateful for any
suggestions as to the best value, but without comprising on comfort -
it's a long journey for a kid's first ever flight.

The child speaks French and English, and has a couple of pairs of skis
she'd like to arrive in one piece! (Far more important than the rest
of
luggage, to her mind).

PG
--multiplaza.nl.nu--