Oh, you’ll have fun. As far as clothing goes, there are two considerations: pack for A) the weather, and B) the water.
For the weather, take an assortment of fleece jacket (L.L. Bean Super 200 Fleece Jacket, $69), waterproof rain coat of some sort (Patagonia Lightning, $199), and fast-drying synthetic underwear (or wool, such as the Icebreaker brand). No cotton, so leave the Levi jeans at home. Take footwear that can get wet and that will dry reasonably quickly. As you might expect, lots of dry socks will come in handy too. Take gloves to keep your hands warma good choice would be a “dot grip” glove like Manzella’s Outlast Grip Glove ($12).
In the boat, it would likely be prudent to wear a wet suit. This isn’t a big ticket itemyou want a Farmer John-style bib suit to keep your torso and legs warm should you end up in the drink or just get wet. Warmers 3mm Titanium Farmer John is fine, selling for $119. You can get real fancy after that and wear boating-specific tops, but that can get expensive. I think a jacket such as the Lightning will suffice for kayaking. Alternatively, Kokata’s Action Jacket, at $120, offers good waterproof protection at a reasonable price (beware, though, it’s made of coated nylon, so you’ll poach in the sun).
Of course, wear a PFD, or “personal floatation device.” Won’t do to stay warm if you sink to the bottom…