Depending on your current experience level I'd say the choice to learn C++ with UE4 is either reasonable or catastrophic.
I've been coding C/C++ for a good ten years now and while the UE4 engine is pretty well documented with a fair amount of examples, I'd compare it to trying to learn to surf and swim at the same time. It's not necessarily that the C++ is too advanced, it's just a beast to get started with since it is such a huge engine.
In my experience, the best way to learn is by doing and by understanding what's being done. Diving head first into UE4 C++ might feel like you're wrestling this beast of an engine instead of learning what is actually going on. My advice is to start with something much simpler, either just a text/console mini-game or check out SDL/SFML and fiddle around with some 2D and C++.
However, if you are more inclined to actually make a game than to properly learn C++, then UE4 with Blueprints should be just what you need. You can keep learning C++ with both UE4 and small side-projects while you create your game, just don't expect to go in and create a game in UE4 C++ directly, would be my advice!