Data entry/Data cleansing

We have a database of nearly 3000 entries many of which are duplicates (30%-50%) which need to be put into the correct format for our new database shell. Both sets of data are in excel and the new database has 16 fields to transpose the original data into. We will need duplicates removing and the new data to be transferred into the new database shell although some re-ordering of fields will be required. A knowledge of UK postal codes will be advantageous to make sure the addresses are correct.