I applied last year (I may again this year if my job prospects are bleak), and I managed to get through to their regional manager interview (One step below the ass centre) before I was rejected for 'not understanding the business (!?)'. Anyway, if it's like mine, you'll have to go to their head office in Watford, sit in the reception and then taken upstairs for the interview.
In fairness, the lady was nice and the questions were the usual questions which you would expect at any interview for retail, just with the added twist about Wine, it's fairly simple.
The regional manager interview was also undertaken at the head office with, and asked similar questions but with more depth, and more questions about retail, the company and wine, the courses you may go on and so on..
The pay isn't that fantastic, for what you will be doing (I visited a store beforehand). You'll be basically a trainee manager/sales assistant/wine taster/shelf stacker, in fact any role in a retail store you can think of, that's what you'll be doing.