I don't think the widget world system is meant to have a constant pressure, it's just meant for topping up.
I'd get proper gas (or my halfords bodge) and regulator and a universal barrel hose. They fit S30 valves. Can't remember the diameter of the hose that comes with it off the top of my head though although IIRC I had mine connected to an 8mm fitting so that would make it 5/16".
Blimey, that all sounds a bit expensive for a noob like me !. Only just convinced the mrs the £200 + ive spent already on 2 kegs, fv's, gas, kits, spraymalt etc etc etc i going to save us money in the long run. reckon i will have to get a few succesful brews under my belt first before any more major outlay.
Thanks thoug