Apple TV is very easy to set up. As long as you already have an Apple ID (iTunes), it's just a matter of plugging the power source in, plugging an hdmi from the unit into the tv and it takes you through it, asking you to enter your ID. Easy to use too. You can purchase/download through iTunes on your computer, select download later, then watch them through the unit, or you can buy through on the tv.
There are lots of alternatives out there now. I also have a Chromecast which is even easier to set up and use. Look at the various devices and see which apps/services suit you the most. I mainly wanted Netflix. Some of them support BBC iplayer, the ITV one, Demand 5 etc and some don't.....you may be able to do a comparison on a site like Currys/PC World.