Completely disregard Coldfuzion’s post. Download Rekordbox (it’s free) and use it to put your tracks on usb sticks. After that you’ll need a pair of headphones and some hi fi speakers. We can’t give you any recommendations if we don’t know your budget.
For software I recommend Rekordbox. But if you like to use your setup together with a computer then you should get Mixvibes Cross (not CrossDJ) it has full HID integration with CDJ350. It’s to only software I know of that has HID and not just midi for the cdj350.
What does that mean? well you can use your CDJ’s to control the software and you get track info displayed also on the CDJ screen. You can also use the CDJ’s as sound card. Mixvibes Cross is €79.99 or $99.99 and you can import Rekordbox liberary and get all hotcues, loopsnd memory points and beatgrids imported.
As for speakers and amps. If you are going to be using them at home get some decent cheep studio active monitors
I don’t know much (hardly anything really) about speakers and amps, but a quick look at decks.co.uk tells me you may not be able to get a descent amp plus speakers for £85.
Something you don’t need to think about just now but can consider down the line; you can get a tsi file from the Pioneer website that allows the CDJ 350’s to work with Traktor Scratch without using timecode cd’s.