Looks like there was an active group there a few years back but doesn't seem to be active now.
Maybe add Staffordshire to the title of the post to attract the interest of people near you.
There's also a new Country Smallholders group on facebook, you could post on there to see if there is anyone local enough to show you how it's done.
As to the age it depends. Our first cockerels were 6 months old, we didn't hang them and they roasted up really nice. The next two batches were the same age, again not hung but really tough, they did slow roast ok though. If you're worried about toughness you could try hanging them after slaughter, if not then slow roast/cook to be sure.
Dans