Hi again, it's been a long time!
I moved back to the UK in 2019, no issues with that. But now, due to personal circumstances, I'm having to move back to Aus, (luckily I got citizenship while I lived there ) Again, no problem, I'm looking forward to it.
In the UK I have a state pension coming in, plus I will be renting my house out. When I get to Aus I will not need to draw on these as we have a small income there.
So I'll be leaving the pension and rent build up in a savings account, and will only need to draw on it in emergency.
Are there any potential problems with this which people can see? Will it affect my tax situation in Aus? Do I have to inform HMRC that I will be expat?
Any/all advice gratefully received.

Your pension will be taxed in Australia and it will be taxed when you get it, even if it stays in a uk bank. If you intend to stay you need to inform HMRC you are no longer resident.
There are also issues with renting your Uk home and tax. You should ideally get some tax advice from someone who can do both Uk and Oz tax. BDM and GM tax are both good.

Also DWP re state pension - residents of Australia (among many other former British colonies) don't get the annual pension increase, so it is critical that the DWP is informed when you leave the UK/ relocate to Australia as to fail to do so could look like fraud (attempting to get the annual increase when you don't have the right to it).

If you return to live in the UK, let the DWP know and your rights to the annual increases will be restored.

Thanks both.