Vlookup Postcodes

Hi - I'm trying to use vlookup to search on postcodes.

For example - I want to vlookup this postcode SL6 4UB using the SL as an anchor. This will go into another worksheet and will then provide the location Slough. I'm unsure on how to do this though?! Very basic grasp of Excel!

Something like:

PHP Code: 

=VLOOKUP(A1,B:C,2,TRUE) 


Where Column B Would have a list of all the prefixes and C would have the town names.

The list would need sorting alphabetically

Cheers fella! Legend!