Hey Karotka,
to import any model to UE4 you have to get it in .fbx file format. I don’t know if sketchup can do this, if not, try exporting the sketchup model as .dae and import this into any 3D-Modelling software, such as 3DS Max or Blender. Unwrap the model (there are automation tools for that, no woories doing this by yourself), export as .fbx. Import to ue4 - that should be it 