Remington still makes it. You should be able to order it from any full service gun shop, like Del Selin's in Vernon, BC. In fact, when I was in there last friday, they had some on the shelf. The ammo in the enfield revolver should rightfully be the 38-200.
The 38-200 really turns the little round into a manstopper. When the Geneva convention, banned lead bullets, the Brits had to go to a jacketed bullet. They were kind of limited for space so they made the bullets lighter, because of the copper/nickle jackets.
If you can find hollow base bullets and load your own, these pistols can be very accurate. It isn't advisable to shoot HBWC in them though.