Hi !
Glad you managed to solve your issue 
In the recently released 1.3.0 version of datasets, you should also be able to reload your dataset with no internet connection with
wiki = load_dataset("wikipedia", "20200501.en", split="train")

Indeed if there’s no internet connection, this will fall back on the latest wikipedia dataset that you’ve loaded with load_dataset, and notify you with a warning.
In your case it would look for a processed dataset in “~/.cache/huggingface/datasets/wikipedia/20200501.en”
Let me know if you have other questions !