I will reply you here.
1. Open CIMB Sg account.
https://ringgitfreedom.com/banking/opening-...for-malaysians/
2. Open interactive broker account one you are able to login to CIMB SG account.
https://www.interactivebrokers.com/en/home.php
3. Enable trading permission for UK market
4. Open up Sunway money account
https://sunwaymoney.com/
5. Use Sunway money to transfer RM to SGD into your CIMB Sg bank account
6. Use FAST transfer to send money to IBKR SGD bank account using CIMB sg.
7. Convert into the currency you want Interactive broker
8. Buy Ireland based S&P500 ETF off London Stock Exchange.
Why Ireland etf and not US  based etf?
Go for Ireland based etf cause you save 15% on dividend tax vs 30% if you buy US based ETF directly.
If you want to go for options down the road, go with US based ETF namely SPY.
More info kindly read this post and the ringgit freedom blog.

Avoid lifebalance steps or recommendation for ETF. Not cost effective and lousy. Use the above steps. Anything you can ask here or ask in
Interactive broker thread
Or
https://t.me/sgIBKRcommunity

Unlike him who don't want you to talk about ETF investing, I am all ears if you want to ask about EFF investing

Btw, he reported my post in the insurance part for pointing out that he's wrong and his steps are expensive and inefficient.

I have no idea how you find your Australian account. You can fund IBKR directly using your Australian account.

To bring money back, try their fintech. They have lots of fintech there. If all else fail, use wise but make sure it's open under Australia if possible and not Malaysia cause wise is kinda of restricted by Malaysian govt laws.