Process took a couple weeks. I applied online (2nd June) then a couple days later I was asked to attend a recruitment event, which was about 2 weeks later (June 20th). When I've received my confirmation email about my interview, I made sure to read through it all as they tell you how to dress, which is dress the way you think represents River Island, they also tell you to bring proof of your right to work in the UK, you must bring it else you can't do the invterview. (Do NOT bring your drivers license, it won't count and you won't be able to proceed with the interview ether).
Thankfully for me, there was only 5 of us, so the atmosphere was very calm and relaxed. We were all taken to the staff room, then asked to tick our availability (they definitely seem to prefer people with good availability). We then proceeded to do an icebreaker which was really chilled and funny! After that, we were put into groups of 2, then taken down to the shop floor to do a little game. In your pairs you were given an event e.g Festival, Date night, children's party. Then we were asked to pick an outfit and explain why we picked it, so it was pretty straight forward and very easy if you're into your fashion :) We then went back to the staff room, asked any questions that were on our mind and then it was done in less that 2hours (the interview can be up to 2hrs). We were then told we would here back by the end of the week, if you weren't successful you'd get an email and if you were successful you get a phone call from one of the managers, I was lucky enough to get a phone call yesterday offering me a job, although they did take longer than they said but if you don't mind waiting, it's worth it :)