i don't know what the weather is like there, but you can't go wrong with a denim skirt, leggings, and a vintage tee...and you can jazz it up with some accessories. then you can be more comfortable too.
i bela fleck. i categorize them with jam band attire so i would probably just wear jeans/or a denim skirt, a tank and comfy shoes. maybe do fun earrings or necklace, but i would keep it simple (with minimal accessories), and flats.
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"i tell you one lesson I learned
If you want to be something in life, You ain't gonna get it unless, You give a little bit of sacrifice, Oohh, sometimes before you smile you got to cry.." -The Roots
I wouldn't worry too much about your outfit. Prepare yourself for some dirty hippies and semi-conservative Baby Boomers.
Maybe a jersey knit dress and flip flops? Is it outside? (sorry if you already mentioned that) If so, you might opt for jeans and a cute top ... but bring something long sleeve for later.