Forum Moderators: buckworks
Royal Mail Reseller Search Page [royalmail.com]
I think the best data you can use for this will be the Royal Mail PAF file. It contains all the information related postcodes, areas, counties towns etc. The problem is it's not cheap and it's an annual licence.
Mack.
If you purchase the data (and annual license with quarterly updates) you will spend around £1200 on that alone. Then you'll need to get it working, and then you'll have to have a way to manage the updates...
It's easier to subscribe to a service.