Although you may own your smallholding, you do not necessarily own the shooting/sporting rights over the land. So, before you let fly with both barrels at that sly old cock pheasant who has been making a nuisance of himself in the vegetable garden, check your title deeds, as otherwise you could face prosecution for poaching.
If you don’t own the sporting rights, all is not lost. The Ground Game Act (1880) gives you, the occupier of the land, the inalienable right to kill rabbits and hares on the land that you occupy, irrespective of anyone else who holds the right to do so, and the Deer Act (1991) clearly defines landowners and occupiers as people authorised to take deer on the land that they own or occupy. Also, your title deeds may specify certain pest species that you are permitted to kill, such as woodpigeons.