Hiya Scar and welcome to WAB. Shame about the trees
You have to be carefull what you plant in terms of conifers etc. However, if you don't have anybody overlooking you at the rear, you could try some quick growing evergreens. They are cheap to buy (2-3 quid) and grow amazingly quickly. As Mr Mack says though, if you have the patience, go for some nice large shrubs or fruit trees. They will feed you and keep the locals happy!
please let us know what you decide. Wizzo