Don't worry too much about engine size, a 1.6 Focus probably wont have a huge difference in speed compared to a 1.2 clio/1.25 fiesta (off the top of my head i've got no idea which would be faster) It will however be a nicer place to be if you crash and insurers should take this into account.
Same story with a mondeo 1.8, probably be able to find insurance in the same sort of ballpark as the smaller cars and pay the same sort of money to buy them, but the mondeo again, nicer place to be, nicer place to be if you crash.
Recent Corollas have been dull dull dull, I think with a bit of thought (and asking people is a good start) you should end up with a much better car history than your dad... Unless his old corolla was a fettled AE86
Don't dismiss the classic thing as well btw, your looking at car+insurance and budgeting £3k, with a bit of thought and a good deal you can get insured for £500 or so through a specialist, pick up something stylish for £1k and blow the rest on cola and rugby players *ahem!* Only young once