Lets say that you could do this. Not saying it isn't possible.
If it was though:
You would basicly die. In order for this to happen the astral connection to your physical body that your soul needs would be disconnected. You would no longer be connected to your body so you would basicly be comatose with no way to return.
Your soul is also designed for your human body. Thus, even if your soul was other than human, it has human limitations while connected with your human shell. even though you soul has the ability to transform to certain degrees when you astral project, you still have the astral connection or 'bridge' that would still limit it.
The point to this is that if you were to connect to your guardian angel, your soul would not be able to handle the sudden rush of energy and power and knowledge and would combust. This would be because a guardian angle or spirit is that, a guardian so they have a different soul, a different composition than our soul's do.
Another theory is that the guardian entity would just absorb your soul up and you wouldn't exsist anymore. You would just be apart of the guardian's soul or energy.
In short, best not try it. Your guardian wouldn't like it because one, they don't want to connect with you soul, and two it means that your not understanding your lessons or following their guidance and essentially that means (in their eyes) that they aren't doing their job right.