I agree with some of the posters above who suggest going on a shorter trip to start with, possibly even a supported ride. Maybe you could find a short tour route near you that sticks mainly to cycle paths or rail trails to deal with your traffic concerns. However, as a serious anxiety sufferer myself, if the root cause of your issue is anxiety itself, you will always be able to find a reason to cancel a trip. You might plan a short trip on cycle paths then find yourself overwrought with worry about coyote attacks, or pay the money for a supported tour only to cancel at the last minute out of fear that you won't be able to keep up with the group. If in your case it's just fear of the unknown holding you back, then yeah, just push through it, get out the door, start the wheels rolling, and you'll find out the things you worried about aren't so bad after all. But if you find yourself overcome with anxiety about the trip or some aspect of the trip, you probably need to work on yourself to get at the thought patterns that are causing you to fixate and build the anxiety separate from whatever current cause you might be directing it at.