Hi mate,
I dont know if anyone else has got back to you about the Security Clearence! The only way you would be able to get SECRET Clearence is if you are Military in a specialist unit dealing with Secret information or operations, Police in a specailist unit or Security Services or any of the above in a Country who is a member of NATO. Clearence has an expiry date of when you leave that unit. You can sometimes get it if you work for a company who have Military contracts....
Hope this helps
Dave