...I still can't believe what passes for 'winter uniform' at all schools here...when I was growing up, Winter Skirts were affairs made of pleated wool, and reached the ankles. Any shorter would be silly, as you'd get cold legs!
Now, winter skirts are the same length as summer uniform, and wow, that ain't long at all. (The Summer uniforms barely cover the girl's bum these days it seems.) How is that supposed to keep you warm??
At least at our school they brought in the option of pants for girls. Not very comfy, woollen, nothing like the trendy dungaree-type pants the boys got....but hey, they were pants.
Maybe if more schools had pants for girls, there'd be less stupidly cold legs around...

So yes, I feel your pain.
I hope you find a decently long skirt soon!
Op shops are definitely worth browsing through. :-)