Good Luck to everyone applying. History at Oxford is such a great course (I study it at Christ Church). There is a huge variety of period choices you simply would not get at other universities.
To ensure interview success make sure you can talk cogently about a particular aspect or period of history that interests you- and try to read up on some historiography, knowing the difference between a marxist, social or political approach is always helpful. More advanced candidates may want to even venture into the realms of Pocock's work....