Our front garden is only 5m deep and 37m wide - the lawn slopes up the hill too which emphazises the lack of privacy I think.
I want to put hedging along the width of the plot but dont want to take too much from the garden itself. So i'd like a hedge that is dense (and preeeettty) but economical on space- do these exist? We would need a 7ft hedge to effectively screen the reception rooms.
My other thought was planting palm trees or something similar? what would lend the garden a feeling of depth?
I'm sorry I can't answer your question about which plants would work best. We wanted to do something similar but when we checked the planning rules for our area it only allowed 3ft hedges or fences on front gardens that boarded the pavement, so it may be worth checking the rules in your area.
Our council (Merton) had some basic details on their website and you could ring someone to discuss if you wanted more detail. To be honest lots of people on the street didn't pay any attention as many had high hedges anyway. We opted for shutters over the lower part of the window, it suited the style of the house but might not work everywhere.