I just had a look at the NAMHO website there are still places on the Winch and SRT trips into Snailbeach deeper levels, there are easier trips intop Potters Pit and Rhadley Mine and probably one that should not be missed Crickheath (or Swan Mine) its usualy closed off due to bats and landowner water sup[ply and trip not to be missed.
There are trips into Clive Mine )easy apart from a simple traverse) a Full SRT trip into Huglith Mine, walk into Scott Level at Snailbeach (again landowner permission rarely given)
http://www.namhoconference.org.uk/2011/front.htm