Since the break with Rome, the C of E doesn't do dispensations. There's allowed and not-allowed, period.
I think that's true of Protestants in general. The dispensation business had become just a Vatican money-making racket, along with indulgences etc.
But affinity between the parties can only be created by the former marriages of the parties themselves, not by a marriage of any 3rd parties.
Which means, if you've been married before, you can't marry certain blood relatives of your late spouse.