I bought the hand-wheel versions of the 540 and 580 nipple/nut fitting (rather than the wrench versions), connected to 1/4 npt pipe, and I connected this to a female DIN fitting. See the pic and link for more information.
http://www.northeastscubasupply.com/.../adapters.html.
I put male DIN fittings on both ends of my fill whip. So, I can just screw in the male DIN connector to this or any other supply tank with a similar connection. I prefer this to the quick disconnects.
Sorry, this is not a UK source. But, I hope this will give you a start for what to look for.