Postcode look up has been introduced:
  1. To make it easier for you to enter property details
  2. To improve the accuracy of the map on your ad
To complete the address info simply:
  1. Enter the postcode in the two boxes (e.g. EH12 and 3AB)
  2. Select FIND to view the full list of addresses for that postcode.
  3. Select the correct address for your property.

I don't know the flat number.
The Royal Mail database returns addresses with the flat numbers predominately in a numerical format. For example, 8/7 Tenement Street. The first number is the street number and the second number is the flat number. We realise that particularly for flats in tenement buildings you may have the flat number in an 'F' format eg 3F3 or 2F1. You may not know what flat number this relates to eg 3F1 could be 7,8, or 9 depending on the style of tenement building. If this is the case select an address which has the correct street number and enter the Flat number (in F format) in the 'Apartment No' box.

My flat address doesn't appear.
The postcode database is the most up-to-date available from the Royal Mail. For new developments it sometimes takes a few months before this database is updated. In the meantime select a postcode which displays the correct name and enter the street and/or flat numbers in the 'Apartment No' field. You can always update this at a later stage when the postcode has been released.