Help me with my holiday

Hi, I am an Australian travelling for the year with a friend, and from the 29th of July to the 2nd of August I will be visiting Kythera. I am 18 years old, with an Australian license of 2 and a half years, and would ideally like some accommodation, and hire a car. Please give me advice on cheap accommodation and car hire. Some rental companies will not rent me a car due to my age. Thanks Evelyn