As an asthmatic I found it hard going inside the mine as it is claustrophobic and very damp... water was dripping everywhere. So, aside from having to step over water puddles everywhere, which made the already-uneven floor rather slippery, the walls were dripping too.. so there wasn't much to hold on to!
At the end of the mine you have to climb 82 steep steps, which I found hard going, bearing in mind my chest was already bursting and needing dry air, plus the fact I am not that fit!
There is more information about this cave tour on my Things To Do tip about it.
Matlock Bath (2 miles from Matlock) is very popular with tourists. Avoid in a car at weekends!!!! The traffic can get horrendous, especially through the summer. Walking is a much more enjoyable option.