Worked in one (Bexleyheath) for over a year.
The interview will ask about your knowledge of films/games/technology etc, providing you can talk about one of these in a semi-understandable way they will most likely offer you the job.
If the store is already open and trading, expect to be invited to undertake a trial day (basically a day of unpaid work) where they will properly evaluate your performance, and then proceed to hire you regardless of how you perform.
Also as above, everyone below Supervisor is on a 0 hour contract.