I used to put the premium diesels in my company cars (before the bosses insisted I buy the cheaper stuff), it did make a difference but not a huge one.
You'll maybe get an extra 10-15 miles out of every tank with premium diesel. My wife also used to use it her Audi A3 (about 4 years ago) and interestingly the premium fuel did NOTHING to alleviate the DPF problems that plagued the A3.
For what my opinion is worth, I'd stick with standard diesel, but from a quality provider i.e. BP, She'll, Esso.