You are correct. As long as you have not admitted the debt in writing within 6 years and a CCJ hasnt been obtained then the debt is unenforcable. The creditors can still chase you for the debt but they cannot go through the courts and apply for a CCJ.
There are many templates on the net for sending the creditor a Statute Barred letter. Like I said, you cannot stop them from chasing you for debt but they cannot take you to court to pursue it.
As for being "written off", they will still chance their arm and hope you pay up not realising the statute barred law.