If OP is not moving until January then he's resident for all of this year so (assuming he's working for the whole year) he's not due anything back for this year.
Sybil
if you're a PAYE worker and work for all of January, your credits will likely be averaged over the course of the year so that you will be likely to get a portion of the tax paid in January only repaid. You'll have to fill in a P50 after you move and then wait a while for a repayment - they may insist that you wait until 2012 as they couldn't be certain you wouldn't come back to work in 2011.