The First World War Poetry Digital Archive, in conjunction with Merton College, Oxford University, have made available some letters between Vera Brittain and Roland Leighton. Roland attended Merton until enlisting. This could be of interest to anyone considering a project on Brittain.
http://www.oucs.ox.ac.uk/ww1lit/collections/leighton
It is also worth looking at Merton's page about the war and its former students.