Not so far from the truth. A teaser for episode 10. , shows Derpy & Tick Tock accidently marooned on a paradise world.
This happens when The TARDIS goes wonky and disappears; while the Doctor was inside making repairs. When this happens.. Days, months, and years will have past before The Doctor returns. In that time; being alone with each other would draw them closer. Who knows? Tick Tock may be the father of Derpy's baby , Dinky..