I looked at these levels years ago and they didn't go far.
The deep adit goes but entry releases large amounts of ochre so its best kept out of. Nothing much to see in there anyway.
My recommendation is to join the Mines of Lakeland Exploration Society, you can visit the Keswick museum and do this at the same time.
They organise some good trips for people of all levels of expertise.
My avatar is a poor likeness.