I’m working on a project, where I want to compose an shoe sole with different lattice forms in different parts of the sole, but I am a complete beginner to grasshopper and rhino, so I’m worried the learning curve will be too big to be able to learn this software and achieve my project in time. Do you think this is achievable?
You got this—don’t ever doubt your learning ability.
But: how much time do you have left? 
Clarify this?
Do you have a starting shape? A surface or mesh?
A shoe last? 3D scan? A sketch?
Much on this topic can be found on this forum if you search properly.
One thing is to finish your project in time, another is to start and keep learning like all of us 