Sixth Form Business Dress

Before I start I just want to apologise for for any spelling or grammar mistakes, my English skills aren't great at the best of times and I'm currently tired af.
My school has recently decided to go for business dress at sixth form. Great.
The dress code consists of:
- Jacket and skirt OR
- Jacket and trousers OR
- Jacket and dress
I don't like wearing trousers, I can't be arsed to wear a dress everyday so the only option left is a skirt, however being the prude I am I'm not a huge fan of tight pencil skirts, but tight pencil skirts seem to be the only business dress type of skirt.
Are there any other non-tight type of skirts I can wear?
I don't want to blend in with the lower school, I'm really short compared to everyone else. I'm coming from a small all girls school to a large co ed school, at my old school I was slightly below average and at my new school I'm practically a midget.
There is the option to wear an abaya (the long dress thing Muslim women wear) however I'm not willing to convert and I'm not fully on board with the whole Shariah law thing.
Any feedback would be much appreciated.
Big love Annie x

You should be able to find a knee length pleated skirt during back to school season, then find nice blouses and a blazer to go with it

Thanks, are pleated skirts acceptable for sixth form? I've only seen girls wear pencil skirts and tube skirts
Really appreciate your reply.