I would recommend you to start with a combination between a 3d program, the UE4 and some theory stuff (words that you need, how do games work,…). So start watching tutorials and try to create a simple game just with some basic meshes that you have made and basic blueprints setups.
“Learning by doing” that’s how I started game development and I have learned pretty much in those 1,5 years since I started
So yeah, I would recommend you to buy the engine (it will just cost you 20$ → because you can also cancle the subscription after you have bought it and you will be still able to use it) , download a 3d program (blender is a pretty good choice) and go into the game development adventure!
By the way, it would be good if you could post such stuff into the forum. 
https://forums.unrealengine/forum.php