Before the initial interview they asked you if you want an interpreter, sometime it will take longer then expected or interpreter was busy serving other clients. you wont get an interpreter on spot you have to wait.
@ addicted.. we dont need to notify them whether you want interpreter or not. if you need a mediator try to appoint him/her before the interview date. so you dont need to find them at last minute.
in wife case we did not hired interpreter and VO did not even ask whether you need interpreter at the time of interview.
@ angel and am4u2ster, thanks guys for ur suggestions. Regarding the interpreter, my family and my husband suggested that i ll be okay in english. I think i was just scared bt now i am fine. Thanks guys.