The steam iron idea will work. But don't start spending money or energy on this problem till you have the kit in hand. I don't know which kit you're getting; most of the wood ones, frankly, aren't very good. But the Vikings knew what they were doing (even if the wood kit manufacturers don't). The actual Viking ships had sweet, gentle hull curves that, to a large extent, were established by the natural bending tendencies of the wood. Depending on what kind of wood the manufacturer provides, you may well find that no steaming, heating, or other radical methods are necessary to get it to assume the curves you want. Lots of the European companies use beech, which is extremely flexible. Others use walnut, which isn't.
When you have the kit in hand, do another post. Maybe some of us can offer some more specific suggestions. Good luck. It's a great hobby.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.