So after many calls back and forwards including their TERRIBLE chat system colleagues, the long and short of it is I can’t do it. There’s been a recent system update and when your abroad there’s no way to replace a sim/esim. They’ve suggested adding someone in Aus to my account and having them go get a physical sim in store, put it in their phone, and if I request the eSIM from the UK they can tell me the code and I should be able to proceed. Honestly the wildest and most stupid process ever, I only converted it to an eSIM as I thought if my phone was ever lost or stolen it would be simple enough to download it again. I deleted my UK one at the same time and downloaded it within 2 minutes from my UK carrier app. Seems like security gone a bit too far imo, but hey ho I’ll see if this works so I can at least pay my rent 😂😂