This is an indicative list of what trees maybe in flower or bearing fruits throughout the year. It is not an exhaustive list, but an informative listing to encourage readers to explore further, and I suggest the Collins Book of British trees as a starting place.
The following is a list of trees that will carry fruit or berries during January as food for birds and ground feeding animals. The only deciduous trees that will carry leaves are oak and beech, All coniferous trees will bear leaves.
This second list contains a selection of berry/fruit bearing bushes plus taller seed plants found in hedgerows, all of which providing food for winter birds.