You can't buy stalk adaptors for Ripspeed headunit, as they are a Halfords own brand essentially.
Manufacturers like Autoleads/Connects 2 will do most major aftermarket brands like Sony, Pioneer, JVC etc.
Oh and don't bother with the Ripspeed unit anyway. Honestly just don't! Its tacky, most likely will go wrong within a couple of months, and is just generally awful. lol.