Typical office warm-wear for me includes:
Knee length dress (Boden, M&S, Next....) with sandals
Ankle-skimmer/cigarette trousers (Zara, Mango, M&S....) and short-sleeved top (Boden, M&S, Monsoon) with ballet flats or sandals
Knee length pencil skirt, as above
Combine any of the above with smart cardi or jacket if chilly
Dresses tend to be jersey wrap dresses, fit-and-flare, or shirt dresses.
For tops, I tend to go for something hip length, more formal than a teeshirt, for example today I'm wearing a Boden short sleeved broderie anglaise top. I also have several cotton knits. I rarely wear shirts as I don't like to tuck things in.
Legs are now "out" for the summer, and won't be back in tights until the autumn!