You can have a splendid few hours in Coniston without gear, with lots more to do if you're SRT competent.
Well worth getting hold of a copy of Eric Hollands field guide :
https://www.amazon.co.uk/Coniston-Copper-Mines-English-Ddistrict/dp/0902363360 On the right up the Red Dell side of the area, Deep level can be followed via a relatively new cross cut for quite a way, although (unless it's been dug out) it's a bit wet at the entrance now.
Taylors and Flemmings levels further up are solid as far as the stopes. It's well worth looking into the top of the Engine shafts, Bouncy level etc. Lots of interest.
On the left hand side going up from the youth hostel area, Hospital level goes a fair way with several branches. There are a couple of holes in the floor with planks over them and a fixed traverse line - a harness and cows tails might be wise.
At the top of the hill there are several entrances near Levers water, but all require ropes and SRT gear. The through-trip from there to Hospital level is very good, but needs gear, route finding and care.
There are several surveys on here in the 'Coniston re-discovered' series of documents, well worth reading the documents.
Have fun!