Might I suggest that a clown suit would be appropriate.....
Seriously though - just turn up in normal civvies (Jeans with shirt or Jumper - nothing too officer, just not chav), make sure that they are in good repair and have been threatened with an iron. You'll be OK - good luck.
dont wear 1, ripped jeans 2, trainers 3, tracky top 4, any thing you would wear with your chav mates on a street corner. make sure its all clean. Read your JIs as it will state in there smart civies, every intake lads come in shit clothes then i make them get changed there and then as there smart stuff is in there bag. First impressions count alot!!!!!!!! get your hair cut as well
Back in 1988 when I started at Arborfield a couple of lads turned up looking like hippies which the training staff all turned up at the hairdressers to watch the fun as they were shaved. Its up to you if you want to have it done beforehand my lad did las year when he joined and when he still had to queue up for the haircut parade the barber trimmed it but never charged him for it. As long as you turn up smartly dressed and with the right attitude with all the kit on the JI's you'll be fine and passed the first test.