Sod the sensible side, get one!! I'm a student, in second year, had a series 3, 3rd year a 200tdi disco and now for 4th, probably a scooby legacy haha. I was unlucky and bought a **** disco, everything that could break did so I've cut my losses and I'm breaking it. I would however like another, but since it's final year, want to concentrate on my work completely and not spend time offroading and denting my car. I WILL get another one though once I have a proper job and another car.
My advice is to go for it. HOWEVER...Make sure you get a good one, check for a FSH, cambelt changes, RUST, RUST and bit more RUST!
I would recommend getting a good set of sockets and spanners though because it WILL come in handy and if you get a good one shouldn't really cost you much.
Hope the advice from a fellow student helps!
PS, with regards to been sensible, I had a petrol series 3 for a year as a first car, how bad can a disco be!