The Olive is from the Oleaceae family and this is a genus of over forty species and they make great bonsai trees.
Olives are evergreen with opposite thick leathery leaves and originate in mild climates of the Mediterranean regions but spreads out across more temperate countries in naturalized forms. Olives are widely cultivated for their fruit and historic groves can be seen right across the Mediterranean. The Olive most likely seen in the UK is that of Olea europaea and this is a hardy form with grey greenish leaves and fragrant white flowers in late summer.
This is a great starter bonsai tree too if you have space indoors as they are not frost hardy and prefer warmer all year round conditions so can be kept in a conservatory or on a window sill if there are good levels of light and heat. They like free draining soil and grow well, requiring plenty of pruning, which in turn allows a shape to be developed fairly quickly.
For more information about starting an Olive tree from scratch check out this link- http://bonsaitonight.com/2012/05/29/starting-an-olive-bonsai-from-scratch/