What shall I wear for school mufty day?

Mufty day's next week at my school (when you wear your own clothes) and i'm not sure what to wear. i was thinking of wearing a floral skirt knee length skirt with leggings, and a sort of cream coloured top with buttons on it tucked into the skirt. with a cardigan. thing is, it's england, so im not sure if it'll be raining..is that okay?(the outfit?)