No, you just need to create a new field in your feature class and use the [Field Calculator][1] to create the unique ID based on fields in the class. Something like:

    "CH%s%s" % (!StreetField!, !UniqueCodeField!)

using Python.

  [1]: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Calculate_Field_examples/005s0000002m000000/