personally i'd suggest the TA rather than OTC.
OTC's have - can have - a certain reputation for being home to a strain of humanity known as the complete to*ser.
do you really want to hang out with 19 year olds in red trousers braying everywhere?
join a TA unit, get yourself properly trained and sort out a short tour over the summer, or even a full six month job (build up and post op leave will take you to 11 months) by taking a sabatical.
it will give you vast experience, enormous confidence and you'll have a massive headstart at Cranwell.
(my TA unit, in Birmingham, were very understanding about academic deadlines and study time, they also sorted out a 3 month tour for the summer of years 2 and 3, giving me lots of cash and a fabulous addition to my CV.)