[senco-forum] resignations

I know that someone out there will know the answer to this one!
A dear friend of mine who is still teaching at the school which messed me about so badly last year is so miserable that she bitterly regrets not handing in her notice in May.
Does she have to wait til Christmas before she can leave, or would it be possible for her to give 3 months notice now and leave at October half-term?
She is desperate to go, so any advice would be welcome. Her own sense of professionalism will not let her go off sick.
Thanks,
Barbara
Inclusion Unit Manager,
Preston.