To begin with, none.
To start out you'll need to go to an archery club, and they'll let you borrow some equipment while you get started.
In fact, clubs should let you borrow stuff all the way through the six-week introduction course to the sport, and most will let you carry on borrowing it afterwards as well.
If you find you're really getting into archery and what to buy your own kit, the clubs will help you pick exactly the right stuff for you.
And it's a good job too, as a full set of kit could cost between £100 and £300.
You'll also need to join a club, but as a junior member it shouldn't be too expensive.