If you don’t ever make any mistakes, you might well be the first. Like life, camping is a process of trial and error (and usually the first errors come in putting up the tent). So don’t worry about not getting everything right, the main idea is to have fun and enjoy the great outdoors.
To answer your first question, you don’t need any permits for camping – it’s not like fishing in that regard. As a beginner, you’d be best advised to start off on a campsite (where, of course, you do have to pay, and often book in advance in the busy season). That way you’ll be around other campers who can offer advice and assistance, and you’ll also find more facilities available, such as showers.
However, there’s also what’s called wild camping, which is pretty much what it says. Largely, you can camp anywhere that’s not obviously private property, national parks are fine, although you need to be aware of some rules, which include no more than two nights in one place, leaving no trace you’d ever been there, and so on. Of course, yes, there are places where camping is prohibited, but in most instances these will be well signposted.
Many farmers do let people camp on their property, sometimes free, sometimes for a small fee. You’d need to ask at a particular farm to find out the details, though many do advertise on the gate.
Finding More Information on Camping and Trekking
Where can you get an education on camping and hiking? This site has a wealth of great information, of course, but most shops that sell hiking and climbing gear will also be able to give very good advice. Don’t be afraid to ask questions, they’re always happy to answer, and many of the staff are avid hikers and campers themselves. Of course, you’ll need the right equipment to begin with. Make sure you have a good tent, backpack, boots and jacket, at the very least, and a comfortable sleeping bag. Practise putting the tent up and taking it down so you’re not completely lost when you go camping for the first time.
As to maps, you really can’t do any better than OS maps for the area where you’ll be hiking. They offer all the detail you’re likely to need. They’re exceptionally accurate, with all the topographical features, and easy to carry (you might consider a clear map case to hang around your neck for ease when walking).