Wanting to plan a 3 week holiday in June/July to the Greek islands and Croatia . There will be 5 of us travelling and we will be coming from Brisbane , Queensland Australia. I have been reading that it can be quite difficult getting from for eg . Santorini to Croatia . We can be flexible with our itinerary . Any suggestions fellow travellers ?

Historically there have been few (if any) direct flights between Greece and Croatia but things may change - there's certainly plenty of demand for it. Croatian Airlines did have some but don't know whether they are still available. Try www.amadeus.net, Croatian Airlines and Aegean Air for airfares. You may have to fly via another port.

The only way to reach Croatia from Greece is with Croatia Airlines. Have a look at their website.
I checked some random dates in July, and the prices i saw for a flight from Athens to Zagreb or Dubrovnik were around 300 Euro per person.

Random date June 30th:
Santorini dp 11.05 - Rome FCO ar 12.20, Fares start at 60 EUR
Rome FCO dp 16.40 - Split ar 17.45, Fares start at 50 EUR
http://www.easyjet.com
check also http://www.blu-express.com

PS The only way to reach Croatia from Greece directly*