This book is the best I have read for beginner to intermediate endurance cyclists:
http://www.amazon.com/Complete-Book-.../dp/1579541992
How easily you can do the event depends on how fit you are now and how much you can train between now and the event.
I'd recommend doing shorter faster rides during the week and a long distance slower ride on the weekend. I'm not a big fan of intervals for non-racers but if you get motivated by and enjoy a more structured training there's nothing wrong with it. But if you don't have any base then pretty much any riding will result in an improvement.
No one can tell you how much you should be riding because we don't know how fit you are or how well you recover. No one but you knows that. The basic training principle is to cause stress then rest. You need both to improve. Many racers work on a weekly cycle and then a macro cycle of 2-5 weeks. Each week in the macro cycle builds up stress and then you take a "rest week" (which isn't an entire week with no riding) to recover. Then start the next cycle.
If you need a plan with numbers the Bicycling Magazine century training plan has worked for a lot of people.