Yes you can just show up. If you email them, they'll probably let you come early to "qualify"; they want to know that you can safely handle a firearm. More here:
http://massasoitgunclubinc.com/. Click on "how to join" on the left.
I've been a member a little over a year and like it. These guys really want to encourage new shooters, so the guest policy is good. They have a rimfire pistol team, and they sponsor mini USPSA style shoots throughout the winter as an intro to the action shooting sports. There's a really nice upgraded range (for members only) in addition to the somewhat dated original range where guest can also shoot. I understand that the old range will be getting a significant upgrade in the not-to-distant future.
Only down-side for me is no outdoor and/or center fire rifle range. On the other hand there's no work requirement either.
PM if you have other qustions.
