Problems importing an asset bundle

Like many of you guys, I need to export asset bundles to be loaded into my game when necessary.

I have created a directory in my project called MyAssets, I intend to bundle the contents of this directory into an asset bundle.

For now, all that this contains is a 3D Cube object, for test purpose.

What I'd like to do is load this in during the game and see my cube in the current scene. Sounds easy! :-) But I cant get this working(!)

Ok, code for export (through the IDE as a menu option), taken from the numerous examples and documentation:

     [MenuItem("MyTools/Export test")]
     static void Export()
     {
         string assetFolder = "MyAssets/";
         string bundlename = "TestBundle";
     
         UnityEngine.Object[] assetPathsList = GetAtPath<UnityEngine.Object>(assetFolder);
         Debug.Log("Loaded " + assetPathsList.Length + " assets at path: Assets/" + assetFolder);
     
         if (assetPathsList.Length > 0)
         {
             Debug.Log("Creating asset bundle: " + bundlename + ".unity3d");
             BuildPipeline.BuildAssetBundle(null, assetPathsList, "Assets/" + assetFolder + bundlename + ".unity3d", 
 BuildAssetBundleOptions.CollectDependencies | BuildAssetBundleOptions.UncompressedAssetBundle, BuildTarget.StandaloneWindows);
             Debug.Log("Finished building asset bundle");
         }
     }
 
     public static T[] GetAtPath<T>(string path)
     {
         ArrayList al = new ArrayList();
         string[] fileEntries = Directory.GetFiles(Application.dataPath + "/" + path);
 
         foreach (string fileName in fileEntries)
         {
             int assetPathIndex = fileName.IndexOf("Assets");
             string localPath = fileName.Substring(assetPathIndex);
 
             Object t = Resources.LoadAssetAtPath(localPath, typeof(T));
 
             if (t != null)
                 al.Add(t);
         }
 
         T[] result = new T[al.Count];
         
         for (int i = 0; i < al.Count; i++)
             result[i] = (T)al[i];
         
         return result;
     }

This seems to work fine! Then I come to the import side of thing. Which Im not 100% clear on yet. I have created a script with the following code in an attempt to get working:

 using UnityEngine;
 using UnityEditor;
 
 public class Importer : MonoBehaviour {
 
     // Use this for initialization
     void Start () {
 
         string path = EditorUtility.OpenFilePanel("Load Bundle", "", "unity3d");
 
         Debug.Log("Creating asset bundle from file " + path);
 
         AssetBundle assets = AssetBundle.CreateFromFile(path);
         
         assets.LoadAll();
         
         var loadedObject = (GameObject)assets.mainAsset;
         
         Debug.Log("Instantiating object in scene");
 
         Instantiate(loadedObject, new Vector3(0, 0, 0), new Quaternion());
 
         Debug.Log("Instantiated object successfully");
     }
 }

I wasnt sure where to apply this, so for test purposes I applied it to a panel in my scene, hoping that instantiating would make the imported asset a child of the panel but it gives me the following error:

ArgumentException: The prefab you want to instantiate is null.

Can someone help me by pointing out what I'm doing wrong? :-)

Thanks in advance guys!