Ok, I've had an email saying your maps articles are all well and good if you know the postcode. For some of the work I deal with for example Party Wall, it's kind of important to have the full address, especially for undertaking land registry searches to establish the Building Owners and Adjoining Owners details.
So I pop over to the Find a Postcode function on the Post Office web site at http://www.postoffice.co.uk/postcode-finder
There are Four little search filelds
OK I actually know the building number and the post code as this is my work address, but for this example assume I don't. So above I have only entered the building Name, Street and Town - then click on the Find Postcode and........
The full postal address including post code and a nice little location plan to boot!