I am about to replace the rear discs and pads. Can anyone advise me on how to? Is it the same as the fronts?

If it's got an electronic handbrake there is a safety procedure to follow to isolate it. Have a look on You Tube as there are probably videos of how to do it. The pistons in the calipers usually need winding in on the rears rather than pushing them in as you do on the fronts. 

I think the MK1 Kuga is the same as my Mondeo, you'll need to release the handbrake, so chock your wheels and then release the cable from the caliper, then you need a wind back tool (or long nose pliers, but harder to do) to wind the piston in.

A kit like this one does pretty much every callipers made. It has both left and right hand threaded wind back tools, as some rear callipers use left hand threads.

Once reassembled, I also pump the brakes before applying the handbrake otherwise your handbrake won't hold the car (until you let it off and pump the brakes again).

I agree with the winding of the caliper piston. Installing the first three pads on the front and right rear of the TC was easy. But once we got to the left rear, the piston didn't want to go back in. we had to twist and turn with slight down force to get the piston to go back in. if you think you don't need a special tools, think again. Better rent one from you rental shop if one is available. we had to make this up as we went along. Several sized vice grips etc and after 45mins of doing this, we finally got the left rear pads installed. 

Image: Left Front (passenger side) with new Powerstop carbon fiber/ceramic pads.

8 minutes ago, LostInTransit said:

Better rent one from you rental shop if one is available

We don't really have shops that rent out hand tools in the UK. The majority of the time it's not much more to buy one to keep (especially a calliper windback tool which is sub £20).