Upvote:1
You don't need a transit visa for Sydney as you can see here. UK is included in the list of countries that doesn't need it.
Also if you hold a British passport you are included.
Transit without visa arrangements
3.- People holding British passports (irrespective of endors*m*nt in passport regarding national status)
Upvote:6
According to the Australian department of immigration, you need a transit visa unless all of the following conditions are met:
Otherwise, you must get a transit visa. It's free, but you must apply in advance, after booking your flight and if necessary obtaining a visa for your destination.