I work by liverpool street/bank, so see every kind of formal attire I think!
If you're going to a job interview and you're wearing a short skirt, then you need to be in tights, absolutely. Flesh toned/Tan tights, but tights nonetheless. I think you'll roast in black tights, I'd put them away for a few months, but yes you do see people wearing them.
I don't wear leggings very often, but general rule is, unless you want to really show off and have an awesome body to show off, make sure your top covers your bum. Leggings are not really job interview appropriate!
Generally people are wearing ankle boots and shoe-boots but not knee-high boots, mainly peep-toes and slingbacks.