I don't know what the Brit Companies offer. All I know is, you go buy something at your local parts house, be prepared.
In the old days, there was a line called "Mountain Master", I think it was, that WOULD stop the car....but wore out four times faster.
Softer linings generally equates to faster wear.
But not sure what you need, other than new linings. I don't think I've used over-the-counter drum brake shoes in 15 years. Power disc, yes, but not shoes.
On relining.....before you start, know what you're doing. Takes a "touch" to get the tight yet not fracture the lining material. You haven't lived until you have one come loose on a winding mountain road.
Another thing......riveted is actually better for fade than bonded.
The gasses have a place to go (rivet recess) other than floating your lining. You could always tell when riveted lings got worn, as there was no longer any place for the gasses, and they started fading....at least as I recall.