Welcome along. Not being a strictly cosha hobby everyone will have their own "rules" for me its about...
Not breaking in, not stealing & not wrecking everything, this keeps you on the right side of law as breeching any of them means you are committing a criminal offence.
Sharing locations is the big debate, personally I will only share with someone once I know & trust them. I have spent years building up my locations from many hours hard work but I know others will give anything to anyone. IMO this just leads to places getting prematurely wrecked which gives everyone less opportunity to enjoy them.
Safety is important, its best to pair up with someone if you can though most of us have done numerous stuff solo, get some decent boots & clothes as u will get ripped up to hell for sure & be very wary of unsafe floors, I know several people who have had life changing falls.
If you want to get into underground stuff you are best to join a local caving club (you have some excellent underground stuff in south wales) as this is the most dangerous element of exploring.
Hi Nat welcome to the forum if you just stick with that bit of excellent advice off bikinglyn you should be fine , we have loads of interesting places here in South Wales for you to see but if you struggling there’s plenty of us from s wales that could point you in the right direction