There are some performance related issues and there are a few things you can only do in C++ … but having said that … your best bet is to start working on your game and see how far you can get with just Blueprints … the result may surprise you.
If you experience any performance issues then you can convert those to C++ … but I surmise that depending on your game you might not experience these performance issues.
By the time you get to the limits of Blueprints (if any) you will probably have a pretty decent game already and then getting someone to help you with C++ or learning C++ on your own shouldn’t be too much of a hurdle.
Good luck with your project. 8-}