My wife and I plan on visiting Australia for about 6 months. My wife is Filippina and I am British. Can anybody advise on how to get visit visa's longer than 3 months.
Depending on your age you may be able to apply for the WHV (Working Holiday Visa) which is valid for 1 year, with the option to extend it for another year if you do 3 months eligible work. For more details visit:
Working Holiday in Australia visas and Extended Working Holiday in Australia visas.
If that does not help you you can also have a look at our visa overview page for other visa options such as the professional worker visa, sponsored work visa, etc, by clicking here.
Good luck, I hope that that helps you somewhat.