Postcode search facility

Hi,

I’m looking for a plugin that I can use to create a postcode search facility on my website. I have a business with a range of different branches and I want customers to be able to put in their postcode and find their local branch. However, I do not want this to be their nearest branch. Instead I would like a certain number of postcodes assigned to each branch (e.g BA1 1, BA1 2, BA1 3 etc.) It may be that someone will be near to one branch but that the branch which controls their postcode area is actually a little way away and so when they put in their postcode it is this branch that will come up.

I think what I’m looking for is some sort of search facility that is not necessarily designed for use with locations but would be able to search a predefined list and direct users to the correct page based on their location.

Many thanks in advance if anyone knows how to do this.