I'm guessing you mean don't bother with a GTE unless you can charge it easily, preferably at home.
I tend to agree. A PHEV doesn't make a lot of sense if you don't charge it, and to charge the small 13kWh battery on public charging probably isn't going to be economical.
Asking "How long will the battery last?" is not easy to answer. In GTE mode, the car will top up the battery and keep it around 50%, but of course, it's using the ICE engine to do that. The hybrid mode will gradually run the battery down, but how quickly depends on how fast you accelerate, top speed etc.