I have never been in, but I know the enterence and am up for a visit though I won't do solo in that cave. The enterence is very unstable. Nobody from Brynmaur seems willing to go. Once a few people mostly from Brynmaur went they were also most of the local cave rescue team. Cave collapsed while they were in I think they dug themselves out.
If this does not put you off the idea pm me its just a place I won't go solo.