Richie's link doesn't work for me either, but I found this one

http://uk.support.tomtom.com/app/ans...full-postcodes

But I'd really be tempted to take it back, get refund and use your phone. You already have one of the most powerful search engines in the world on it (Google), it has full turn-by-turn real-time navigation, and you carry it with you anyway, so why something else that a) could get stolen and b) doesn't do what you want it to anyway? (I know it should, but it isn't)