I would personally buy something like a Mondeo. I'll now explain why.
At this end of the market, everyone wants a small car. They are economical, cheap to run, low tax, and ideal for new drivers. As you've seen, £3k doesn't buy much Fiesta - its going to be quite old. The same is true of things like Golfs.
The most important thing about the car market is that car values are based on peoples PERCEPTION - what they THINK is the case, not what is actually the case.
It is perceived that a car like a Mondeo (Or a Passat, or a Mazda6, or whatever) is expensive to run, drinks petrol and is bigger than you need. This means demand for this sort of car is low - and as a result, so is price. You can pick up all manner of fully loaded cars of this type with leather seats, climate control, etc etc. They also have decent 2 litre petrol engines.
But you might say, I'm only doing 4 miles each way! I dont need a big engine!
Nope, you dont. But they are such great value why not have one anyway? Because you dont drive much the difference in actual money per month spent on fuel between a Fiesta and a Mondeo is pretty small. And a nice big comfy car is a nice place to sit whilst you are stuck in traffic.
Think about it like a promotional packet of cornflakes. You might not want 1Kg box of cornflakes but if Kelloggs were offering 50% extra free on your usual 750g box you'd take, it right?
Think of a Mondeo as a Fiesta with 100% extra, free!