I'm a UK 16 and I wear skirts, in fact, I often feel they look better on me than jeans although it took me a long time to realise this! Tulip skirts are awesome, they kind of go in at the bottom like a pencil skirt so give a great hourglass figure.
At the end of the day, nobody is too fat to wear anything if it's what they want to wear and feel comfy in.