It never stopped me from creating songs and solos. I think I have a good hear. I didn't at first so if you don't think you have one, it comes with practice.
The best songs I created came up in a jam, by myself with a 4 track recorder. I always tape myself when playing. It's now natural, I sit down and decide to improvise and TRY new things. It's in these quick 30 minutes recorded jams that I come up with the best results.
When I play I just know when it's not right. It doesn't sound right.
Like Raskolnikov said, "you can't do that, it's not in this key." That happened to me while jamming with a accomplished studio guitarists. It just shutdown my creativity. The best advice I can tell someone is "let it flow". Just play forget the key forget all of this for just a moment. You'll be amaze of the results. Unfortunately, you'll need to understand some theory when the time comes to mix your riffs with the other band members or adding other guitars to your riff.
Guitar is just like life, there's more than you way of doing things and get to the same result. Find the one best suited for you.
