As said Blender should be fine to start out with, it’s close to the functionality of the paid alternatives, so especially if you are new to game dev I’d recommend saving the money, at least in the beginning. Popular alternatives to blender would be Maya, 3Ds Max & MODO. Some people stick with Blender and others prefer the alternatives, you might as well start out with the free option.
For the landscape you might want to use another program for the rough terrain, and then fine-tune in the engine:
[Free] Scape: Scape: 5. Overview and downloads
[Paid] World Machine: http://www.world-machine.com/
Some of the models you might want to create in a Sculpting program, since this is easier with more complex models:
[Free] Sculptris: http://pixologic.com/sculptris/
[Paid] ZBrush
For texturing you might want to purchase one of the following:
[Paid] Substance painter: https://www.allegorithmic.com/products/substance-painter
[Paid] Mari: Mari | High Resolution 3D Painting Software
For basic animations & character models you might want to take a look at https://www.mixamo.com/ (still free as of writing)
Other places you might want to look at:
[Tool thread on the forum] [Community List] Free Software Tools & Resources List - Audio - Epic Developer Community Forums
[Some of the links from the recent game jam announcement] Summer UE4jam! June 29th - July 4th - THEME: BLESSING IN DISGUISE - Announcements - Epic Developer Community Forums