Which trees do you prefer? This, of course, is a matter of personal choice; however there are other conditions to which trees will thrive in your own situation. You must look at closeness to boundaries and buildings, exposure, soil conditions, shade, hardiness, site lines and final height. A good starting point is looking around to see what trees there are in neighbouring gardens and parks.
Not all trees are suited to all soil types, so you should check this out to start with. It is possible to get acidic soil, chalky soil, wet soil and dry soil; some trees will thrive in them, whilst others will not.
It is possible to get soil testing kits from your local garden centre, or contact the Royal Horticultural Society and they should send you a sample. If you quickly hit clay or rock when you are digging your garden, don’t panic as there are trees that thrive in very little soil.
There is a limited range of weather in the UK and a tree’s survival can be affected by salt from the sea and exposure to winds. There are some tree species which are suitable for changeable weather and are unlikely to grow above 15-30ft.
Look out for Betula (birches), Crataegus (thorns), Malus (apples including crabs), Prunus (cherries and related trees) and Sorbus (rowans, whitebeams etc). For some situations look at Acers (maples) and Salix (willows), also the evergreen Ilex (hollies) or perhaps small conifers.
You may be best off visiting a public gardens where trees are labelled, before making your final choice. This will give you a fantastic way of viewing the tree, and you can judge them for yourself. There are also some fabulous books available to judge trees, or look in the internet.