I don't live in either of those countries. Plenty of apps aren't localised for every region, and plenty of people speak English as a second language. I can decide for myself whether I want to use your app or not, the App Store already tells me which languages it supports. English also happens to be my first language, but if it wasn't, I'd probably still prefer to use it instead of some automated translation.

Also sorry, but why would it take a week to release in the UK and Australia? You literally click a few buttons in App Store Connect, and you're done.

From someone who's released a few apps, keep in mind every localisation has to be updated whenever you make a release after changing your copy/UI and can considerably slow down early-stage development. It can be a great way to expand later on, but I'd be cautious about trying to support numerous languages out of the gate.