Had a look on the revenue website and there is no Form 12 for Tax Year 2010, I have all my medical and other receipts and P60 so why wait?
Anything wrong with sending in a 2009 Form 12.
If your employer has filed their P35, which judging by the fact you have a P60, they have why not use the paye naytime facility - enter the med 1 details etc and request a P21.
As a tax practioner myself, I would not advise sending a 2009 Form.