Hi,
there are kits and they used to be in clear bags with yellow print, can't think of the brand. The wholesaler where I used to buy them locally was trying to sell his business a few years ago and the factory is now empty but I haven't found if anyone took over.
Look up a retailer called Darby's in Plenty Road Preston as they used to deal with the same wholesaler and they seem to be able to find all sorts of old stuff. Or try Minisplus in Bayswater, I think they have some of the kits available for brake and clutch.
And if your old ones are genuinely old and not the crap new'ish ones, then I would even consider SS resleeving them if they weren't also done by the same wholesaler that sold up or retired.
Terry