Breweries closest to Winnipesaukee are
Kettlehead in Tilton and
The Lone Wolfe in Wolfeboro. Both have taprooms.
Burnt Timber Brewing & Tavern in Wolfeboro is more of a brewpub (I've never been there but that's what it sounds like). There are others around there but not as close. Depends which part of the lake you're on. Check this out for other breweries in NH:
Beer Map - Brew NH
With Treehouse, the taproom isn't open on Wednesdays. Just Tuesdays and Saturdays. With the increased capacity at the new brewery in Charlton they don't usually run out of the regular rotation beers that they offer that day (usually 3 of the regulars like Julius, Green, Haze, Doppelganger, Bright) but if there's a special release or something they have a 2 can limit on (like King Julius, Very Green, etc.) that usually sells out quicker. Although the 2 can limit is put in place specifically so they don't run out. Either bring a big cooler to put all the beer in or go golfing first. I've never been there when they open at noon but I heard the lines usually are better around 3:00.