As of 2011-04-13, 18000 pounds sterling is 29421 US dollars. Despite what you say about "getting your foot in the door", I would hesitate before taking a job that paid so poorly. For the record, my internship paid $25 per hour. That translates to $42000 per year [1]. I'm not an exceptional programmer, and my grades in school weren't that stellar either. I would strongly encourage you to negotiate before selling your services for so low a price.
I see ads for 'Senior developers' that want to pay £25-33k. Granted there also ones paying better but the highest advertised I've seen is £40-45k p/a. Obviously it will be higher in London though, and there are lots of ads for contractors at £300 per day.
Meanwhile I know people who finished their CS degree and never got a programming job. I know one guy who's a decent programmer, only got a couple of interviews, one only because he offered to work for 14k, but ended up working in a bank admin job for 13k for years before finally getting a secondment to an SQL/Excel position at 18k or so.
I don't know, man. Just seems there's a disconnection between the salaries you guys talk about on HN and the salaries that are realistic for me. Bearing in mind if it's a graduate job then there's going to be many gaps in your knowledge (unless you're exceptional), so it seems you should bite the hand off the first place that offers you a job and the chance to become a more complete developer (after which you'll have a much stronger negotiating position, but until then, as an unproven dev companies can justifiably look at you as a liability).
You need to find positions where they don't look at you as cost-center, and instead as someone providing value to the bottom line. 300 pounds a day is ridiculous. Most contractors make double that in day.
But what if I don't want to move, or don't want to spend anytime in unemployment? £1500 per month is pretty appealing when you have rent to pay. Also, while £18000 might be a joke in the respect that you're only slightly better off than the average admin job, despite the vastly different knowledge and problem solving requirements, what about the whole 'majority of developer applicants can't solve FizzBuzz in ten minutes' thing? Or the belief that programming ability is like compound interest - the more you learn, the faster you get better? Or the outsourcing to India (where I bet they get a whole lot less than 18k per head)? Those things would seem to make low starting salaries natural.
But I do like the idea of selling your skills on a freelance/contracting basis, and foregoing all the noise of the industry hiring practices. I'd definitely give that a shot before taking a 18k-24k job. Seriously doubt £25+k for a first, junior dev role is on the cards though.
1. http://www.wolframalpha.com/input/?i=%2425+per+hour+