I just went back and rewatched the reveal...That has never been revealed. Went from no-one touching them with a bargepole as tenants to overnight moving in to a newly decorated house with a large out of control lab and a baby on the way. And not one job between them. The only thing that made sense was it was a family member renting it to them, no one else would even look at them as tenants.
They originally found a house. The landlord wouldn’t accept them due to their financial situation (Sophie’s ‘self employed wage’ was too low and Dave was on furlough, with a dog, not ideal tenants). It fell through.
They then ‘found a house’ they loved.
They went for a viewing. It had recently been renovated and so they were surprised they got it. It’s definitely through a letting agency as they talk about speaking to the letting agent in depth. So private rent for sure which is even more baffling.