Hi Richard. Welcome to the site.
Most of the heads come apart with a selection of Torx screws. The DC05 Motorhead one is more complex as it has wiring in it though.
Whichever site you quoted is on our site filter for some reason. Looking at the part number 902606-01 in the URL, it is this part?
They come out at about £1.75 plus a little for the card fee and P&P. About £4 all in I guess.