I'm sure Greg or someone who works with him will comment on this, but I wanted to give you my thoughts in hopes that it can provide another point of view, or simply echo their advice.
First off, I agree with Greg's statement. In order to do the full snatch, you have to be confident and comfortable in your bottom position with the bar in the right position overhead and your body structurally sound.
In my opinion, you should be learning/executing the progression drills unless there's some extreme inhibitor (i.e., not being able to get your arms extended overhead due to lack of flexibility, shoulder issues, etc.). Granted, you're probably not comfortable with the going into a full squat with a dowel/bar overhead -- you're probably experiencing the common limiting factors that most endure, such as a lack of thoracic extension, shoulder immobility, and probably some ankle flexibility issues. Still, if you can get into a solid starting position and power snatch position, then the progression drills will help you. As of now, you're limiting yourself in what you can learn rather than identifying the things you can do and seeing which drills would help you reach your goal of being able to execute a snatch. Does that make sense?
In my own experience, I had an Masters-aged lifter begin to learn the lifts from scratch. He lacked ankle flexibility, which started the chain of problems: collapsing torso, shoulders unable to sustain a bar, lack of squat depth, etc. Still, he was able to get into a solid power snatch position. I taught him the progressions and continued to teaching him the power snatch; after each session, he would spend time squatting and stretching. Now, he is able to execute a full snatch, but he would still be trying to learn the snatch had I not taught him the things he could learn with the tools and capabilities he already had. For that particular lifter, it made the transition to a full snatch a lot easier. For me, the bottom line is that you can stretch all you want, but you're not going to gain the flexibility needed for, say, the front squat, unless you actually execute the front squat. Coupled with the dedicated stretching/mobility sessions, motions will begin to feel a lot more natural.
Obviously, each case is individual. Please take into consideration your own limitations when deciding how to approach your training, but know that limitations don't last very long with dedicated training and focus.
Lastly, if you can get yourself to a facility that has a quality coach, then I would recommend taking advantage of that available resource.
Hope this helps,
Javier A. Sanjuan
Olympus Barbell Club
Dear God, please help me lift heavy and be awesome. Thanks. Amen.