Sorry, thought you mean't extra bits for the trap kit.
Obviously the inch & a half pipe set up below will need to be altered anyway to do away with that original trap set-up below, the pipe can be moved across to the other side of the new trap then ( the 1/2 bowl side).
Alternatively...
As previously said ditch the B & Q junk & buy a bowl & a half McAlpine kit. Obviously it will need trimming to suit outlet height & centres as all sinks are different. Guaranteed trouble free once fitted. You won't need any extra parts, it's all there in the pack.
As youv'e now discovered B & Q...