When i import my tree from blender to ue4 it doesnt work and neither does my material and stuff i have on it, I try the fbx export and when it loads into eu4 its all messed up
More detail would be useful, in what way is it “Messed up”?
Personally I have experienced issues when exporting from blender>FBX then importing to blender, where the model gets distorted (For instance limbs facing the wrong way.) Is this what you are experiencing or is it something else?
Make sure that you use a right material setup -> take a look at my free vegetation pack to see an example 
Most important is, that you enable “two sided” in the material + that you have uv mapped your mesh