Mark, i really think that opiates are one of the worst things you could take.
If you're looking to feel less isolated, less lonely and less desperate, opiates are pretty much the worst thing you could get into.
Opiate abuse - and addiction (which non-medicinal opiate use almost inevitably leads to) can really shut you off from the world and open you up to vulnerability and misery on a completely different level.
Not wishing to sound like i'm lecturing you, but i've been down the opiate road (like lots of people here - you're right) and i can assure you that opiates (whether it's codeine or heroin) won't solve a single one of the issues you mention.
It won't solve them, but it will probably make them worse, and it will definitely create more, far scarier problems.
I've taken lots of drugs so i try not to be a hypocrite if i'm warning someone about some drug, cos i've tried pretty much everything - but opiates won't help you feel more connected with people.
They do pretty much the opposite of that.
Maybe temporarily, if you're high, you might feel more comfortable talking to people, but generally when it gets to the point that you think you've eliminated your social anxiety, the reality is that you're so mashed that the people you talk to are probably thinking "wow, this guy is off his face" - so they just nod and smile.
Thinking back to my opiate days (daze) - there were times i thought i was really doing great, but in hindsight, i think it was just obvious that i was a mess, and people were just being polite by not saying anything.
If you feel like people don't know how to relate to you now - opiates aren't going to help that.
Do you know how people look down at opiate users? Some people will instantly dismiss everything about you if they think you're a junkie, or even if they find out you use opiates occasionally.
It's not a class of drugs that builds communities - you really withdraw and disappear within a world of your own on opiates.
but i think the loneliness and despair of opiate addiction is guaranteed to make your life feel a whole lot worse, and it's not something you have any control over, once you develop a taste for opiates. Best to stay away from them - i wish i had, but i didn't, and i was addicted to the shit for 10 years.
Just my two cents mate.