Hi hack,
I painted my last boat in two pack paint, i used two types. On the deck i used two pack marine,which did not allow for any flex and movement in the timber. The two pack polyutherane (black ) which i used on the underside, appeared to buff up much nicer in the end result. It was also cheaper than the marine grade product and you got more in the tin. Try a bristols paint shop. Just be wary that painting in winter can really present its own difficulties, so you will need to find some way of heating up the boat after it has been painted.. But two pack is defiantly the way to go if you have the $$$ and equipment to do so.
Cheers
Harry