I note that a few pubs have nights that are referred to as sessions (some pubs in Dingle for example) but do have the names of featured artists who are playing that night. Is is reasonable to assume that these are more like 'gigs' and that you would not be expected to be able to join in?

Should you go to these (or any other sesions) for the first time carrying your instruments - thus making it clear that you do wish to be able to join in - or should you not take them in with you?

It would be nice to do it right.