Richard
I am sure some people will post some links for you, but I am not sure how much that will help because the standard ranges from highly professional down to barely competent
. And the required standard is so dependent on the venue. There is gulf the width of the Atlantic in what is required between entertaining as a pro in a five star hotel or a big wedding, and going as a volunteer to provide some music in a local nursing home. And you dont say anything about your intentions - will you sing, or just play, what kind of venue are you aiming at, how much prior gigging experience do you have, how good a player are you already??.
I will say this, if you have no experience of professional gigging, going out by yourself can be quite daunting.
Most of us evolve to gigging, if we get to a decent level, play for friends, sit in with some others, work our way to it. It kind of finds its own level.
Mike