Shortening names is definitely the norm in the UK. I work with a Val (Valerie) and two Sues (both Susan), but if you just refuse to answer to a nickname, people will use your full name. But perhaps I was just an odd child. :)

One of the reasons I use my middle name online is that I don't like any of the short forms of my first name and I'm not that keen on the full name either. Helen thankfully doesn't seem to invite shortening.