Buying a return ticket with the option of changing the return date

Hi,

This is continued post from one I posted a few months ago. Because the
original post is older than 30 days I cannot reply. The original post
is at:

http://groups.google.co.uk/group/rec...a78038b219bb7b

In brief my solution is to buy my return ticket (well, really it is
London-Sydney, Nov 13th; Sydney-Bangkok, Apr 13th; and
Bangkok-London May 13th) but I will most likely be changing the return
dates, which are the two flights to Bangkok and the other to London,
because I dont know how long I will spend in Oz and the later dates
arent within range (1 year from now).

Anyway, I have found Qantas to quote me about £800-900 for all flights
with the option of changing a single flight for £65 (£50 + £15 addon
charge). Also, I get my first flight change free of charge. To me this
is the one I am planning on buying but firstly would welcome any
comments. Has anyone done a similar flight itinery? Is the prices I
have been given reasonable? Is there anything else before I sign my
life away (lol) that I should take into consideration?

Any comments would be much appreciated, thanks

Burnsy