Fish Fingers and Custard, Doctor Who

In which Sally Sparrow is a main companion of S5, instead of the Ponds.

S5 - S7

I heard somewhere that Sally was meant to be a main companion, but Carey (the actress) turned it down. I thought it would be cool to have the same plot points of S5, but with Sally and Larry instead. Please bare in mind, that we don't have much of Sally as a character, so a lot of plots and character choices will be of my head canons.