Hi James, i see you’re getting into Unity 
Please share a screenshot here, so we identify the problem better.
About the repeating pattern, it’s probably your texture isn’t ‘seamless’. For example in texture.com, there is an option to ‘Show Seamless Texture Only’ at top right. You can also search Google for ‘seamless texture’.
I’m not an expert but here is my workflow in a nutshell for Unity:
1- Model and apply textures in SketchUp. Basically any random texture, you’ll then replace them inside Unity (Applying a texture -not color!- in SketchUp, also applies a UVW map) (Give both groups and textures proper names. Changing names inside Unity breaks prefab connection if you edit .skp file later and reimport).
2- Use SketchUV plugin to unwrap complex objects in SketchUp. (or use Blender for this purpose)
3- Import your .skp (version 2015) (or .fbx) file to Unity. Change textures with proper ones you have.
4- Don’t forget to tick ‘Generate Lightmap UVs’ in import settings (at Inspector).
Note 1: Photoshop might be useful to create textures (and to make them seamless that are not).
Note 2: Take a look at this Unity Docs: Importing Objects From SketchUp