Tatkal tickets remaining under WL before or even after chart preparation, you get full refund subject to deduction of Rs. 20/- only towards clerkage charges.
In WL ticket case, passengers have not to cancel the ticket but they have just to claim refund. If it's e-ticket, then refund will be automatic to your bank account. No actions needed by passengers.
Continue looking for alternate, as your refund on present ticket (Tatkal WL) will remain same .. anytime you decide. Better you keep your ticket open, if by...
more... luck, Tatkal gets cleared at the last minute at the chart timing, would be good for you. Good wishes.