I hope you enjoy it, and meet some nice people.
We have visited Episcopal churches twice, and the chanting sort of gives me the creeps. They did have real wine for communion, and they made you go up front and kneel in a row to get it. (I watched from my seat, although we do participate at our local Baptist church).
Your clothing choice sounds fine to me. They should accept and welcome you, no matter what you're wearing. If not, then try somewhere else.
The real test for me, is how the people act, and if they welcome outsiders. Time tells the truth on that issue. The truth is, you will find imperfect humans, no matter where you go. It's a matter of what you can accept and enjoy.
I like the charity work! Pay attention to see how much begging they do for volunteers and donations.
Hope it goes well for you tomorrow!