Just been looking at this myself John, the picatinny is universal, but it will depend on how you plan to affix the sling, i.e. Q/D or flush cup type sling fittings.
Seekins Precision do different rails that utilise existing stud hole centres, although T nuts need to be fitted into the stock, videos on YouTube. They have a Q/D hole at the rear of the rail, but I can’t find any in the U.K.
Alternatively, BT rails are available more readily in the U.K., they will also require the T nuts, but they have a built in flush cup.