No they don't do Coldwar at my local Gunman site. They do Camo v/s solid colours, with shooting role rules. Certainly not Coldwar. However there are/were multiple Gunman sites.
https://gunmanairsoftmidlands.com/
Most of the CW games I've played were at Fireball (Bassets Pole). Where there were no such rules regarding camo. It was nice to see the CW kit, but not essential for gameplay. They still divided players by banding arms as they felt it was unreasonable to turn players away. A good portion of players made the effort so it worked pretty well.
I'll concede on the SMLE, I'd seen some rifles ping up with decent kits on them the other week and didn't look into them more than a cursory glance, Turns out they had been fed into my news from an Air rifle site, not airsoft.
This is the image that popped up.
On the Sterling plans. When you see them it's actually not a hard gun to scratch build. I've never seen one in stock. I've seen the Blaster in stock.
http://replicaplans.com/SterlingSMG.html