It would be helpful if you could post the full stack trace, so that we can see which line your error occurs at. In general, the more information you can provide in a question, the better.
In this case, it looks like your full_model_pipeline may somehow become a numpy array. Since you have a one-element pipeline, you could try changing
full_model_pipeline = ...
Try this function to get the feature names.
column_transformer = preproc
new_feature_names = 
for i, transformer_item in enumerate(column_transformer.transformers_):
transformer_name, transformer, orig_feature_names = transformer_item