Hi Pepper
Getting on-water training from a pro is a great idea; the lake would be a better place if everyone did so!
I've heard very good things about Janis at JPBoating, and I'm pretty sure she has a link right here on the site. And, though lots of marinas rent boats, she would probably have a feel for the best location to rent from so you coulld start in a relatively quiet area. (With what you just shared with us, I don't think that the Wiers area would be the best place for you to start; maybe not Meredith or Wolfboro, either.)
I believe that your old CG certificate is still good, but it would probably be a good idea to take the NH course (maybe on line?) to refresh your memory and build some confidence.
Go for it! It's a shame to live next to the lake and not be able to enjoy it fully, and you'd be a great addition to the boating community!
Fred
(aka Silver Duck)