The working holiday visa for Australia is now available to more nationalities than ever before. It lasts for 12 months and you can only ever have one, so make good use of it. Though saying that, recent rule changes include making it possible to extend this visa by a further 12 months if certain criteria is met! To qualify you need to work for 3 months within certain primary industries including farming. Check with employers to whether working for them would qualify. You don't necessarily need to work those 3 months for just one employer. There are a number of Australian HelpX hosts that qualify as suitable employers so look out for those.
The Australia working holiday visa is available to citizens aged between 18 and 30 of Belgium, Canada, Cyprus, Denmark, Estonia, Finland, France, Germany, Hong Kong, Ireland, Italy, Japan, Korea, Malta, Netherlands, Norway, Sweden, Taiwan and United Kingdom.