Traditional is what you make it at the end of the day, but green and red is the classic theme, and in late December your suitable plant options are limited.
Only evergreens are in leaf, and few plants are flowering in the house or in the garden; florists can source flowers from greenhouses.
Norway Spruce or Nordman Fir are more popular for Christmas trees and foliage decoration than the native Scot’s Pine, which is the traditional, semi-retired British Christmas tree that drops its needles all over the carpet as soon as it dries out a little in your warm house.