asx.com.au, in the price sensitive announcements section middle...

asx.com.au, in the price sensitive announcements section middle of home page, click "search past" then look at the most recent annual report of NSE for an overview then look at the latest quarterly cashflow report which towards the end details all shares and options on issue both unlisted and listed.

Sometimes companies do deals (JV's etc) that will require new shares to be issued at a future time, or be issued to directors etc so these won't show up in the above reports. You need to read the last few Quarterly Activities Reports to see what's up in that regard.

So by a little study you will get a pretty accurate idea of the overall share structure.