Could you get some headbands (stretchy ones) made of flowers? I have a potato head so no hats but they look nice.. I think both types of outfits will look lovely, long scarves too for if you get chilly, you can wrap around you?? Layers so some slouchy jumpers that can go over dresses.
Definitely lots of leggings and lots of socks- I change mine at least twice a day especially if it's cold and wet. If it is very wet, your best bet is bare legs (as long as not too cold) you can dry your skin but soggy clothes are just so uncomfortable. DO NOT take jeans. They take up so much room -that could be used for cider- and are awful of wet. Leggings and pretty dressed are my staple along with a couple of jumpers. Oh and hats don't suit me either but I always wear one at a sunny festival. A silly hat is so preferable to sunstroke! Mostly, don't worry too much, just be comfortable and enjoy yourself!!!!
At least one large scarf and a pac a mac that you can chuck in your bag to put on in case the weather turns. Spare socks to sleep in as it gets really cold in a tent. Plenty of socks in general especially if it's wet. Dry shampoo and baby wipes are essential even if you have access to showers, the queues will be massive so you might not get in before you want to be somewhere else. Sunscreen is also a must, even if it's overcast because you're outside all day long, you need to protect your face and any exposed areas of skin. Some kind of hoody to wear if it's cold, cheap and cheerful is best as it will get battered. medium to large cross body bag or rucksack is your best bet so it can be kept close to your body, sadly there are thieves and pick pockets. DO NOT take anything you can't afford to lose, never leave anything but booze, clothes and sleeping equipment in your tent. You just can't be assured things will stay there until you get back. Not really fashion advice as such, anything goes at a festival, some people look immaculate, others look like they've never seen a shower! All good advice though, I have been to many festivals and have found all these things to be essential.