There's rather more cons than pros regarding cars and university. At first sight, being able to hop into it and go home directly rather than having to schlepp it by public transport is appealing. But realistically how many times are you going to be making that trip home? At uni, the car is going to be an enormous financial drain: tax, MOT, higher insurance because you're a student at uni. There's parking, the small matter of whether or not you're allowed to park/have a car where you are and how much the university permits or parking charges are. Finally, you will become your friendship group's Nominated Driver, forever being badgered to collect this, that and the other or 'please can you take me to Outer Mongolia..I'll give you the petrol money'.
Portsmouth has reasonable public transport and the truth is most students manage very well without a car. I'd think very carefully whether it's really beneficial for you to take it.