I haven't done Team in Training either, I'm not much of a fundraiser. If you're interested in training with a group, try and find a really good local running store. They usually have training programs, often for free. You can also check out Jeff Galloway's website. He has a program for training for the half. I really like his run/walk method:
http://jeffgalloway.com/training/half_marathon.html
I don't know my Arizona geography well, but if you're close to Phoenix, they have a USA Fit program there. I did the Austin program my first year and it really helped build my confidence. Almost everyone was a first timer and the cost was very reasonable.
http://www.phoenixfit.net/
I've gone from being completely inactive most of my life to completing 2 marathons. It is a great goal you've set for yourself!