As PB states, £1600 of debt isn't a lot. (I owe about £10,000 and, with a combination of unemployment and occasional casual work, my income is less than yours. I'm still not panicking too much!).
If you're taking home around £900 a month, and spending about £200 per month on rent, it doesn't take a mathematical genius to calculate that you're spending about £700 per month on other things. Your first task should be to try to write down where it's all going to. Until you've done that you won't be able to see where economies are needed.
Let's start with some of the obvious things you need to look at. Firstly, food. I'm not suggesting that you should starve yourself but it's amazing just how much unnecessary expenditure some people make on food. If you're currently spending, say, £3 on a prepared meal (bought from a supermarket) for your evening meal, try cooking something simple for yourself. You can make things like simple (but tasty & filling) pasta dishes for well under a quid. Doing so will save you at least £60 per month.
Sticking with food, what do you do for lunch? If you always eat in the staff canteen or (worse) go to KFC or McDonalds, you're spending far more than you need to. Pack yourself some sandwiches, using cheap but tasty fillings. Doing so might save you around £40 per month.
If you've got energy bills to worry about, try to reduce the temperature of any thermostats. (Wearing several layers of clothing might not be 'fashionable' but it will mean that you won't need to heat your room to more than, say, 18C). Make sure you always switch off any electrical appliances which aren't in use, and that you follow 'green' energy-saving measures (such as never boiling a full kettle if you only want one mug of coffee).
If you list your expenditure there's a very good chance that 'socialising' (i.e. pubs, clubs, cinemas, gigs, etc) will t