Hows this for a goodbye?

Written Notice Of Termination Of Contract

To whomever it may concern,
This is my written notice stating my wish to terminate my contract of employment within Sainsbury’s.

I have chosen to end my contract as the opportunity has arisen for me to able to pursue my chosen career in the near future.
The chosen date for the termination is Monday 20th July 2009.
This is giving the Four weeks’ notice required, of which I will continue to work.

I’d like to take this opportunity to Thank Sainsbury’s, its employees and my colleagues for all the support they have provided me throughout my employment.
Also for all of the new experiences I have had the pleasure of experiencing and the knowledge I’ve enjoyed learning.

I wish all of my colleagues and Sainsbury’s the best of luck for the future,
Thank You once again,

This is a copy of my "written notice"
which i need to give to work tomorrow hopefully.

please make me aware of any mistakes grammer etc. and things i may need to add/remove? 
thankyou thankyou thankyou!