How hard is it to actually construct one? Can you recommend me a book or something to get the hang of it and actually know what I am doing when I am building it?
1. Forget books. They come second, after you learned the basics.
2. Better join an amateur rocketry club. It is "easy" to find one, if not ask the orbiter forum, there are enough insiders here.
3. Get in contact, join a group in your region, learn the basic stuff from persons who not only know how, but also have the experience behind it. A book can't teach you what you can learn that way.
4. After building a few small rockets or working on a large rocket with more experienced people, consider buying a good book and learn how to make your own and fill the gaps, which the knowledge of the other people had not been able to fill.
PS: For building a 2 ft/61 cm rocket, you don't need much, you can buy such kits in online shops (for example the infamous ESTES kits), you just need to be over 18. Using finished kits and reliable mass produced motors is better for the start than loosing one or more hands by making your own rocket motors. But I still recommend you to join a rocket club, not only for assistance in building a rocket, but also for the fun. Launching with friends is far better than standing alone on an empty field.