to set off on a journey in Polish:

1. wyruszyć w podróż

Polish word "to set off on a journey"(wyruszyć w podróż) occurs in sets:

Repetytorium 4: In a travel agency PL/EN
Before setting off on a journey by car
Repetytorium 4: Planning a journey PL/EN
7: Holiday advice on travelling abroad
4.2. In a travel agency