RE: with/without instructor???
While it is possible to learn without an instructor, be prepared to replace and/or repair your plane. An instructor can save you a lot of misery and money since flying RC is not near as easy as it seems. If you can't find an instructor, you might want to consider a plane that has a much higher survivability than the traditional balsa planes. Check out the Debonair, the Spadet LT 40 or the HUhor over at spadtothebone.com. These planes are made from correx and will survive the crashes that you will experience without an instructor better than the balsa trainers.
Do yourself a favor and find an instructor,