Here are some stats for you about the UK job market for web developers (http://www.itjobswatch.co.uk/jobs/uk/web%20developer.do). You can use that in your negotiations with your current employer or to encourage you to look further afield.
You're doing the right thing blogging and posting to github. I encourage you to continue. You are definitely worth more than £15k, even in Suffolk.
You're doing the right thing blogging and posting to github. I encourage you to continue. You are definitely worth more than £15k, even in Suffolk.