Be sure the knickers you buy have a long inseam. I too have a problem with the shorter knickers due to long legs.
The Terry bella knickers have a nice long length and great in every way for me.
I wear long wool socks or leg warmers if I need more warmth. Leg warmers are easy to take off if temps warm-up. Knickers can provide comfort in a wide range of temps if layered.
Living in the cold winter climate I find a need for tights, but overall wear my knickers year round.