There aren't enough graduate schemes for every graduate to get onto one. With a 2:2, although some schemes accept them, you'll probably struggle. Without wishing to be too negative, you're not really in a position to be expecting a good starting salary and prospects of £80k a year - especially in today's job market, that's a big outside bet for an outstanding achiever, and you're not an outstanding achiever. Your MSc does make your CV sound good, but it also sounds very specific, and won't mean much to a HR person unless they're hiring from your field.
It's a strange myth that science graduates have it easy in the job market. Huge numbers of them struggle, it isn't just you. My advice (without really knowing you, this is general advice) would be to get yourself into some kind of meaningful job (doesn't have to be a 'graduate' job - normal jobs may well offer faster progression and less of a tossy environment/hoop-jumping recruitment process) in a proper company vaguely related to the kind of thing you want to do. Once you have a 'career' of some kind, you'll tend to find it easier to progress. Spending too long in retail will make it more difficult to break into 'career' type work. Start low if you have to, but get into the right field.