I was always a little confused about a flat white and thought it was something rather exotic and tricky, thing is though, it is actually exactly the coffee that I’ve been making for myself every morning for yonks.
I use a classic gaggia. Espresso ground Cafe Direct coffee. Make a double shot, steam the (whole) milk to smooth foamy texture and add it to the coffee in 2:1 or 3:1 ratio. The milk doesn’t want be too hot and the ratio of coffee to milk means you have a strong coffee diluted with milk rather than a coffee-flavoured milk drink.
You don’t end up with a massive cup of coffee, it ends up being just the right size so that you finish it before you are sick of it and it still remains the right temperature.
In other words, the characteristics of a flat white appear to be exactly those that hit my personal preference sweet spot. I’ve hit upon them by trial and error whereas I could have saved myself a lot of (happy) experimentation by just asking an antipodean.