I think it depends on where you live. I dont live in Manchester officially,but i spent 9 months here before leaving to go back to the states for a few months. Well now im back and without a vehicle. I found that not having a car was very refreshing. Im fortunate to live in city center and getting around is done by walking and using a very put together public transportation system. Getting groceries can be a bit of a hassle if you have a big list, you would probably have to enlist a cab which can run 5-10 pounds,(outside of London,lol) But there is also the option of online grocery shopping which can run you 3-5 pounds on top of your list.
Any time ive had to leave the city, i found the bus system and trains to be sufficient, but if you choose this route, the earlier you book your tickets the cheaper. If you decide to go somewhere last minute, be prepared to pay. But all in all, i love not driving a car.I get plenty of exercise without even thinking about it, and i love the fact that when I go to a pub or sports bar, i can walk home or call a quick cab. A word of advice though, get an umbrella,it does rain quite a bit.