The house the gennie lived in I persumed was owned by home farm. There is a for sale sign outside it
But then chas told Diane that nickel wanted to rent it out
???

I think she used that as an excuse so that she could leave the pub and go to the house to speak to the Police. Lets hope that Diane doesn't notice the For Sale sign outside it

Hasn't Declan, what with all his dead body on the glamping site and festival cancellation woes put all of the home farm owned properties in Emmerdale (i.e. most of them) up for sale?

I think Chas was just thinking on her feet. With everything else that's going on she probably got the story confused when Diane started hassling her.