As Ron says, it is very easy, I do it all the time.
You will need to buy a DVD recorder, then connect it to your Sky box using a scart lead.
You need to set the "channel" on the DVD recorder so it "sees" what is coming in via the scart lead from the Sky box.
Then as Ron says, put a blank DVD in the recorder, play (or watch) the program on Sky, and press Record on the DVD recorder.
btw I dont think you need to Sky+ it THEN put it on DVD. I think you can watch it on sky and record it "live" as it were.
You will of course need a DVD player, so maybe get a portable one he can put on his lap on the bed.