It sounds simple, but maybe it just isn't. I'm trying to create a database of addresses with a lookup front page. If the user enters a postcode in one box it will give them the possible addresses linked to that postcode in a dropdown. On choosing the required address the three required fields will be automatically populated. The same postcodes will not necessarily mean the 3 data fields will be the same etc, etc. The database may become quite large but there will be nothing more difficult than the above.
I have attached a simple file to try and demonstrate.