...hey Julia, glad its all helping! About the selling v renting.. have you looked online (try rightmove.co.uk) for comparable houses and possible rental incomes? You could go armed with that too. You could do an online quote pretty quick (try Endsleigh or DirectLine) for Landlords insurance too. If you dont currently have your mortgage interest only (?) I would offer to switch it to that too.. that way, it will cost him less in the long run and mean any potential rent would more likely cover the mortgage monthly.. and as you arent going to stay there 25 years, there isnt any benefit in chipping away at the capital anymore as joint owners.

Depends what you want to do.. do you want to keep the house, live in it with a lodger (in which case, I think you should absolve him of all payments/bills).. or buy him out (ditto) or, rent it out (you would then split any costs remaining after rental income has been deducted)?? Whats your goal here?