Just so you know I'm not a tight-**** landlord, in the 6 months of the tenancy I've fixed the toilet cistern because it was leaking and had the ceiling fan in the bathroom repaired because it was loose (despite the fact it was brand new).
Wow, you maintained the property as you are legally required too, congratulations.
I'd get the fly screens too, may not be legally enforceable, but I don't think it's an unreasonable, especially if you want to encourage them to open windows.
I guess some people invest and look at the big picture, while others count pennies.