For selection you dont really need anything apart froma good pair of running trainers, smart clothes and a good attitude.
You will be informed what you will need for recruits course in good time. Dont go buying loads of gucci kit as you may not need it and also on basic they insist that you use only issued kit.
Things i would defo purchase before recruits course is a good bluey (a miniture gas stove) this will save time when making brews. other than that you may not be allowed anything else unless its issued. again you will be informed what you can take with you - that will be the time to ask the questions however dont go overboard as they may see you as a bit of a walt.