Just once did I shop for female clothes as a man, and I hated it, because I felt out of place. After that, I decided I needed the confidence to shop as a woman, and so went out on my first expedition. After two hours in the car in the parking lot of the store I had picked for the experiment, I was still to scared to leave the car, so I drove off, but before reaching the end of the parking lot, I was so angry at myself for failing, that I turned the car around, parked again, got out, got into the shop, and noticed noone was looking at me. Then I felt very stupid :-)
Since then my confidence has only increased (and I don't pass well at all).
Go for it and you'll be very happy with yourself!
Love,
Marleen