Hello Lap,
For my first trip into a mine Sparty_Lea and Ben88800 took me into Smallcleugh, I didn't find it difficult, though I was wary of one area where it was a bit of a squeeze. The area we visited was mostly dry and Ben posted some of the pictures taken that day, these are on the Smallcleugh pages along with a downloadable PDF file with a map of the mine.
I would have liked to see the ballroom flats (apparently a masonic dinner was held there) but due to problems with my car I had to leave a little early.
There's plenty to see in there and I'm sure you'll enjoy it.
When all else fails, read the instructions.