Reading another thread about what things cost more than you realised, and several people saying teenagers, which I'd have to agree with!
But it got me thinking...I've been trying to work out how much we'll need to supplement DS2 when he goes off to uni in September, but I haven't factored in how much we might save as a result of him going. If you've already had teens go off to uni, did you notice a drop in your bills and if so which bills and how much?