The birds of Britain come in all shapes, sizes and temperaments -- from hefty fliers like golden and white-tailed eagles, mute swans and common cranes to small passerines like pipits and sedge warblers.
When seeking to identify a British bird, think about the landscape it inhabits. Britain's contemporary habitat ranges from rugged sea cliffs and windswept moorland to hedgerow and fields to city gardens. The golden eagle favors the empty and desolate country; the common swift, by contrast, can be seen looping over cities.
National parks and other refuges are prime areas for bird-watching---and practicing your ID skills. One of the best lies on the northern Norfolk coast: the Cley Marshes, where over 300 types of birds have been recorded in the area's extensive wetlands.
A good bird book is essential. After a thorough look through the binoculars or the spotting scope, concentrating on major diagnostic features, consult the paintings or photographs in the Peterson Field Guide to the Birds of Britain and Europe, the New Holland European Bird Guide or the like.
There are other sources of information, too---including some of Great Britain's prestigious ornithological organizations. Learn about birding sites through the Royal Society for the Protection of Birds, and consult the exhaustive species lists maintained by the British Ornithologists' Union.