Tip: When asked about my salary expectations for my first job, I said "£20-24k". I got £22k. Many of the other people who started alongside said lower figures - and that's what they got.
Don't quote something way out of the range of the company you want to work for, but don't undersell yourself either. You'll probably get what you asked for... £15-25k is dirt cheap anyway, for any large corporation, but that £10k makes a whole lot of difference to your life.
I think freelancing is a quicker way to get established and reach a high value if you can swing the social and project management aspects. Especially early on, your value increases enormously with each deliverable product you produce. Freelancing allows you to build a portfolio quickly, and you'll be able to point others to jobs you've completed. Successful jobs also inevitably lead to referrals and you can raise your rate on every new contract as your portfolio improves and you become more valuable.
Working for a salary, you can easily get stuck on projects that aren't portfolio-worthy, don't teach you anything that useful, and which you only have a small hand in anyway. And naturally it's comparatively much harder to get pay increases. One solid project that impresses people can take you from charging $50 to $100 an hour as a freelancer overnight. Try convincing your boss to double your salary after 3 months just because you've been shipping good code.
As for breaking in, talk to as many people as you can. Go to meetups, talks, events, whatever is happening, in both the programming AND (very importantly) business/entrepreneurship categories. Just chat and share ideas. If you're confident and you've got brains, people will recognize it, and you'll soon need to beat offers away with a stick. The first gig is the hardest to get because you have nothing to point to in your portfolio. Do this one for free if you have to, or build things on your own. Whatever it takes to get something finished that you can use to prove your competence.
Don't quote something way out of the range of the company you want to work for, but don't undersell yourself either. You'll probably get what you asked for... £15-25k is dirt cheap anyway, for any large corporation, but that £10k makes a whole lot of difference to your life.