Do you even know how far Australia is from Taiwan? Australia also doesn't have power projection last I check they don't have any aircraft carrier and their ships will need to be resupplied somewhere. Southeast Asia have been pretty clear about not taking sides, they won't be able to resupply from there. And finally the current australian govt is trying to mend ties with China. Give it 2-3 months and you will see them making very different stance on the issue

China is Germany's biggest trading partner, their chancellor is the first European leader to visit China to improve ties immediately after Xi confirm his 3rd term. Even if they disagree, they aren't going to disagree hard. Besides, Germany has no power projection. To take part in a recent military exercise in Australia their fighters needed to refuel 5 times just to fly here. You really think they will fight China?

As for the UK, since they are nothing but US lackey I expect them to follow whatever US is doing. Which is nothing. The US dare not fight Russia what makes you think they will fight China which by their own assessment, they will lose. Furthermore to reinforce this point, the US have already moved most of their more advanced hardware like F35 out of the 1st island chain to the 2nd island chain defence to avoid Chinese missile system. They have no capacity to defend Taiwan in asia.

While I'm sure they will try to do something. Like I stated in my last post what are they able to do? Economic sanctions doesn't work and no one even their European Allies are going to support this, direct military means likelihood of losing and providing military support is next to impossible because of Chinese missile system and Taiwan being an island.