First thing is to make sure you have a good backup and the backup is working correctly.
Problems: Had to manually reinstall the console Install location > Tools > AdminConsole.msi
Had to disable then re-enable PXE on the Migration Point http://www.gerryhampsoncm.blogspot.ie/2013/02/sccm-2012-task-sequence-fails-with-bcd.html
Should have uninstalled client on the SCCM server before install.
Had to update Client Installation Settings on the site.