Hi guys I will be In europe from June 16th and come back to Australia on the 27th of September. Yes, I know a long trip but the perfect trip. I have worked out that this will be a period of 104 days. At the end 3 days will be spent in Dubai so disregarding this 101 days in Europe will be spent. Now I know 90 days is the maximum to be spent in the schengen zone. Does that have to be all at one time? I will be in Croatia for eight days and London for four days and I know these places aren't part of the schengen zone. This means I will be spending 89 days in the Schengen zone. Is this allowed or do I need a special visa. My parents are of Greek citizenship and although I was born in Australia can I get a Greek citizenship passport meaning I can stay the full amount of days with no visa? Thank you, could you please help me here and let me know where I can get help from as it will be much appreciated.

That's allowed. For the Greek citizenship question look for the website for the Greek embassy in Australia.

89 days (within 180 days) in Schengen is fine as times in Croatia and UK are disregarded. This assumes you are travelling on your Australian passport.
If you can take out a Greek passport, you can stay in Schengen as long as you like, get a job, study, start a business or retire as you choose.

89 days is allowed in a 180-day period.

Thank you so much I just needed this clarified this has made me feel so much better now haha Thank you for clarifiying. I'm only 20 years old and going with my girlfriend so I'm sure you three all know much more. I will be posting my itinerary soon. Alec,it's a big sightseeing hoiday for now but living there would be great. Thanks guys. Much appreciated.