IMO, there's nothing that good you can do with just a degree in Psychology; you have to do a master's degree for anything interesting. If you look on the British Psychological Society's website, there's a pdf about careers in psychology on there (I'm too lazy to find it for you, but it's easy to find if you google it). Also, the website prospects.ac.uk is pretty good for info on what jobs you can get with what degree you have.