When I bought my drill set from B&Q a couple of years ago, the cordless has a keyless chuck and the heavier duty drill has an SD chuck, like a keyless but the bits have a slot for locking them in, to make it accept standard drill bits I have a separate chuck that has an SD connector and a chuck key for closing it up to the bits, I would assume you should be able to buy a replacement complete chuck with a key if need be, try cromwells if screwfix don't do a key.