Have you seen anything that takes your fancy?
On that sort of budget, you could look at Monitor Audio's Bronze 2's with a Marantz PM6003, which'd come in around £450. If you need a CD player in with that, you can pick up the same products with a Marantz CD6003 for just under £600.
That can get you started - any other details of what you'd like? Floorstanding speakers? Standmount speakers? Big/small room? How loud are you likely to want to play the system?