What follows is strictly personal opinion, in which there's no real reason for anybody to be especially interested. But since the subjects of Viking ship kits and ship modeling books have come up....
I'm reluctant to recommend the Heller and Smer plastic Viking ship kits. The Heller one is supposed to be a scale model of the Oseberg Ship, one of the two major surviving Viking vessels. (They're in the Viking Ship Museum, in Oslo.) The kit looks nice at first glance, but its proportions are ludicrously distorted (the bow and stern are far too tall for the ship's length) and the decorations bear no resemblance to those of the real ship. It looks like the designers worked from photographs (not very good ones) rather than plans. Heller has reissued the thing several times under different names; the one masquerading as a vessel of William the Conqueror's fleet is especially ludicrous.
I haven't looked inside the box of the Smer kit, but on the basis of the box illustration I'm pretty sure it's a reissue of the ancient Aurora kit. That one is a lovely exercise in nostalgia (I built if for the first time when I was six or seven years old), but not, by any reasonable definition, a scale model. Neither the hull form nor the ornamentation bears any resemblance whatever to actual Norse practice. I vividly remember the hours (probably at least two) that I spent with my Testor's glossy paints, painting those crew figures. Some of them even have horns on their helmets. (One of the first things that students of the Vikings learn is that the horned helmet has nothing whatever to do with Norse culture. Wagnerian operas, yes; Vikings, no.) That kit introduced thousands of kids (including this one) to ship modeling, but it's not a scale model.
I'm not familiar with the Billing kit. Billing kits in general tend to be fairly simple and robust, with an emphasis on general appearance rather than scale accuracy. It probably would be an excellent starter kit for somebody just getting into ship modeling.
The most accurate model of a Viking vessel that I know about, though, is the old Revell kit that was labeled simply "Viking Ship" and was released in 1977. According to Thomas Graham's fascinating book, Remembering Revell Model Kits, it was in fact the last genuinely new sailing ship kit produced by Revell of the U.S. (All more recent ones either have been reissues or have originated with Revell of Germany.) It was (according to Mr. Graham) based on a full-size replica in Lincoln Park, Chicago; that replica, in turn, was based on the Gokstad Ship, the other one in the Norwegian museum.
The original Gokstad Ship was buried in a funeral mound, and the bow and stern projected into a different, more acidic layer of soil that ate their upper portions away. The Revell kit includes somewhat questionable ornaments for the bow and stern, but otherwise (if my memory is serving me right, which it often doesn't these days) the kit provides a sound basis for an accurate model of the Gokstad Ship. Unfortunately it hasn't been in the Revell catalog for quite a few years. I have no idea how to find one - other than by checking e-bay.
I can endorse chrisstedt's recommendation of the Lankford book. Mr. Lankford is a fine modeler and an excellent kit designer. His book also has the big virtue of being pretty recent. Its recommendations regarding such things as tools, materials, paints, and adhesives are quite valuable; this guy knows what he's talking about.
The Underhill books, which Dai Jones recommended, are classics. For the purposes of Superdubba's project, though, they have two drawbacks. First, they were written in the 1950s, so they don't take account of modern materials, tools, or adhesives. (Underhill didn't have a really good wood glue at his disposal - let alone epoxy or superglue. And he used a mouth-powered blowpipe for silver soldering.) Second, Underhill was a courteous but firm opponent of kit-built models and manufactured parts. He regarded scratchbuilding as the only legitimate way to build models. I'm one of his big fans, but I don't happen to agree with him on that point. I wonder what he'd think of such things as photo-etched and cast resin parts, which didn't exist in his day.
The Charles Davis books referred to by chrisstedt are in the same category as Underhill's. They're classics, and great introductions to scratchbuilding. (Beware of Davis's reconstruction of the Continental brig Lexington, though, which has been thoroughly discredited in terms of accuracy.) Davis worked in the 1920s through the 1940s or thereabouts, however, so his techniques, materials, and tools need to be taken in context.
I like the Mondfeld book; I think chrisstedt is on target in regarding it as a reference work. It covers a great deal of ground, and doesn't go into much detail on any particular project, but the material in it is generally sound.
Ashey's book is a sound introduction to the hobby. If I remember correctly, though, it deals almost exclusively with plastic and resin kits. I don't think it says much, if anything, about wood ones.
With regard to the Milton Roth book I'm in an awkward position. I don't like to use this forum to make negative comments, or to air disagreements with other forum participants. But I reviewed that work for the Nautical Research Journal some years back, and I have to describe it as the worst book about ship modeling I've ever encountered. It's full of factual errors, mathematical errors, mis-captioned pictures (including a couple that are printed in reverse or upside down), and a writing style that frequently borders on pure gibberish. (I especially remember the chapter about selling finished models, in which the author emphatically asserts that $80.00 x 100 = $800.00. As I asked rhetorically in the NRJ, "should the reader laugh or cry?")
Milt Roth was a retired podiatrist who came to ship modeling relatively late in life and never really built up much experience with it. He was an intensely likable man, and his company, The Dromedary, built up a fine reputation for service and integrity. (It's still in business, being run, I believe, by his widow.) He died, at a tragically young age, while that book was being printed. (If he'd been able to read the page proofs, perhaps he would have made some changes.) I remember the long phone conversation I had with Charlie McDonald, the editor of the NRJ, about how to approach the problem of reviewing the book, which both of us thought was pretty awful. I'll stick with the three sentences I used to conclude that review: "Milt Roth was a first-rate gentleman, and I wish I could recommend his book. His many friends probably will value it as a poignant memorial to a likable, outgoing, and ebullient character. But it is not a sound introduction to ship modeling."
My cordial advice to any beginning ship modeler looking for practical advice is to get hold of the Lankford and Mondfeld books - and the Ashey one if you're working in plastic. If you're interested in prototype practice and the history of ship modeling, the Underhill and Davis books should be early acquisitions for your library. The Roth one should be avoided.
Sorry to be so negative about something, but (obviously) I have some rather strong opinions about this topic. (Opposing views, of course, are more than welcome; that's what this forum is about.) There aren't many good books for beginning ship modelers out there - and bad ones have the potential to drive people out of the hobby.
Superdubba - good luck. It's a great hobby. As you can see, it's inhabited by some strange people. The good news is that most of us are relatively harmless.