Hello there @DanielOS96!
For a starting approach with UE, your texture workflow makes sense to me. Still, before buying extra elements, I would suggest resolving the needs with the tools you already have.
Your process already includes Blender, which you can use to create the materials, and paint your textures. Please check the video guide below, on how to work with just base Blender:
Alternatively, you can modify Blender to operate like Substance Painter:
