We have some hellbores (Christmas Roses) which are planted in a sheltered corner and flower in late December and January.
We also have a number of winter flowering heathers in pink, purple and white which also start flowering in December if it's mild and carry on through into January and February. And winter flowering pansies (which are available in yellow, purple, blue and pink) usually flower all through the winter although a hard frost will usually cause the flowers to sap and wilt.