Look really carefully at the leaves on your plant. Click on a picture that is the closest match to your leaf.

Long and thin and in pairs, clusters or groups may be Scots Pine, European Larch. A compound leaf divided into separate leaflets may be Ash, Rowen, Elder, Dog Rose.
Lobed but hand-shaped may be Hawthorn, Guelder-Rose, London Plane, Field Maple, Sycamore or the lower leaves of Ivy plants. Oval but triangular-shaped may be Silver Birch, Lombardy Poplar. Oval and mostly rounded may be Wayfaring Tree, Goat Willow, Aspen, Hazel.
Oval with rigid spines may be Holly. Oval with a blunt tip may be Alder. Oval with a point may be Beech, Wild Privet or the upper leaves of Ivy.
Oval and lightly toothed may be Blackthorn, White Beam, Crab Apple, English Elm. Sharply toothed may be Hornbeam, Blackberry. Oval with the veins obviously curved around the edges may be Dogwood, Buckthorn. Oval but strongly heart-shaped may be Common Lime.
Oval with bluntly lobed edges may be Oak. A compound leaf divided into leaflets. If it is also hand-shaped like this it may be Horse Chestnut. Oval and long may be Wild Cherry, Almond, Crack Willow. But if it is:
a: Greyish Green: Spindle
b:Toothed and sharply veined: Sweet Chestnut
c:Dark, shiney green: Evergreen Oak

To look for a tree or shrub by name click on the dropdown list and use the scrollbar to find your plant.