Queen Mary's Army Auxiliary Corps was disbanded in 1921, and the WRAF was disbanded in 1920. What other capacities would women have held in the British Armed Forces during the interwar period?
I'd recomend 'corsets to camoflage' by Kate Adie. I don't have it to hand at the moment, but it covers the first and second world war, along with the interwar period. It focusses a lot on the british armed forces. It would almost certainly provide you with some answers.