my understanding is that the cut off date has already gone for normal divi payments ,, But it would be wise for you to find out from Tesco them self since the payment of the special is going to around 50p per share , and the pay out will be voted on at meeting in Feb 2021,
Not wanting to confuse you or anyone but you would also need to see if the share price at the moment has factored in the special dividend , sometimes the share price goes up with everyone already knowing that a set amount of the value of the dividend is going to be say 50p , so after the dividend is paid out the price falls slightly to make up for the pay out.
In the case of SAYE you also need to see what the price per share was set at, it should have been lower than the price it was trading at the open of the saye What is the buying price for the shares you got given 3 years or 5 years ago ? it should show on the letter you got at the start of the SAYE .
Another thing to facture in is the dealing price, and if you expect to hold onto the shares long term.
I have had 5 special Dividend pay outs from other shares and each time the share value dropped after the pay out or cut off date to reflect the pay out I got.