I'd start by building up more stable friendship bases. book an appointment with your personal tutor, and outline that you've 'been bad' but you want to really try to get back on top of things... spend a couple of weekends solidly catching up work, and really make an effort with your friends from other halls. Maybe get a job. That instantly exposes you to more people. Once you feel more secure with your friendship base, THEN go after girls and things. In this state you'll probably crack if you go for her and she rejects you. You need confidence first, and the best place to find this is from a group of friends, or one close partner. As it's risky finding a stable partner in your state, (neither would I advise finding a girlfriend for this purpose alone) work gradually on your friendship base.
Nothing's going to work overnight, but help yourself for once.