It depends where you live, but I would take the train if Angelina is in Cabot Circus; you can get off at Bristol Temple Meads and there are buses running constantly for Cabot Circus - about a 10 minute bus ride.
Unless you have experience of City driving, I wouldn't drive in Bristol, it's bloody horrible. Fast, aggressive, and then there's the business of trying to find your way out of the City to get home; you need a very accurate satnav to navigate the labyrinthian roads of Bristol; getting in isn't too hard, but getting out can drive you to despair. And then there are the motorway traffic jams; you do NOT want to get caught in one of those.
I've driven to Bristol once or twice without incident, but when it goes wrong it goes so very very wrong. I'm interested that Angelina is in the Cabot Circus area because that's not so hard to get to, but I usually avoid Bristol like the plague that it is.
If you have her address, take a smartphone with you (fully charged) and use the GPS to navigate to her place in advance; it's probably in walking distance. Once you know you can walk to her door in x number of minutes, you can go back into town and kill some time in the shopping centre.
Oh, btw watch out for the fcuking beggars. They're everywhere.