You've confused me her thugulike. I think you are misunderstanding the concept of a week in hand. I think it's quite starightforward unless I'm missing something.
Let's suppose you work for 10 years or 520 weeks):
In week 1 you get nothing ,
In week 2 you get paid for week 1
In week 3 you get paid for week 2
............................................................
In week 519 you get paid for week 518
In week 520 (your final week) you get paid for week 519
Then as you leave you get paid for week 520