The prices of foods in Tesco, and of clothes in Primark, are the same across the country. So the only 'costs of living' that you need to think about are those for accommodation (and, knowing most students, local bar prices!).
Most universities urge students to live on campus for at least the first year of their course, so local housing costs are irrelevant. In some of the cities you've listed (particularly Bangor) off-campus accommodation will be almost non-existent anyway. So, if you remain on campus, you can largely ignore the local cost of living. However some universities don't have sufficient accommodation for all of their students to remain on campus for the whole of their course. While places like Brighton will have generally higher rental prices than some of the other cities listed, they will also have a larger number of shared houses to rent.
I see that you're also considering studying locally in East Anglia. Please don't. When I was teaching I always told my 6th form students not to consider any universities or colleges within commuting distance of home, or where they could easily go home for the weekend. If you study at a local university it will be only a place of study and nothing else. To get the best from it, university should be an all-embracing experience. The best parts of university life take place during the evenings and at weekends!
The mother of one of my 6th form pupils once told me "I hate you and I love you at the same time. You've told my son that he should study on the other side of the country, so you've taken him away from me for weeks at a time. But I know that you're right because it will give him the independence which he needs".
Chris