Thank you for your post.
Creating the database of UK postcodes is probably the easiest part of the task. I cannot think of an easy way to map these to a UK map.
One idea is to create a layout that is a map of the UK. On top of the map, you would create transparent buttons that sit on top of the map that when clicked, take you to the appropriate layout and display the postcode. It may even go a step further. That is, if you click on London area, you may be taken to a different layout that shows a map of London. Then, when you click on South Kensington, SW1 or SW2 shows up. Still, you would have to determine how detailed you want the map and how detailed you want the postal code. Do you just want the first few characters or the extended set? SW1 as opposed to SW1 3RH.