The most important thing is that you already know the concepts of programming - variables, loops, conditionals, oop.
BP is essential, simple and is more than enough to start making the game and even to complete a fully functional prototype.
However, as you progress and feel more confortable, you may want to start introducing some C++: a BP node here, an actor there. Nothing fancy, and you will soon realize that UE4 C++ isn’t that hard or complicated.