I retire from my company at the end of the month, my current visa extension of stay is based on a BOI application along with the work permit, these will both be cancelled. My company gave me a letter of termination dated Oct 2015 this coincided with my 60 birthday and at the same time they cancelled my contract and reissued a new contract until April16. My question is do I need a new "termination letter" dated 30th April 2016 when I leave my company for my visa extension based on marriage?

Yes

You need a new termination letter. You will need to go to immigration to apply for the new extension on or before the date on the letter.

Joe many thanks for your advice, I should have the visa extension cancellation mid-month so plan to go to the IMO a week before the cancellation happens. This gives me a week to make any adjustment or additions, but with your kind support I think I'm in good shape.

My biggest concern is that I take the right pictures as I have seen some post that says you should be in the same clothes in the pictures and others saying you need to be in different clothes. I think it will a mixtures but including a shot with the house number.