Sorry, my head has mini suspension loaded into it, I just poked my head under the micra.
I don't think these by themselves would effect the steering axis or scrub radius as steering axis is described by the top centre of the strut and the bottom ball joint, neither of which has moved.
If your aim was wider track you'd need longer bottom arms to go with this wouldn't you? Otherwise it's just going to move the strut closer to the inner guard, unless these are to buy yourself more room to run wider tyres and a more neutral offset without them rubbing on the strut. The wider wheels with the same offset would widen the car but not effect scrub radius. Track width is technically the distance between the wheel centre lines so in this case has not increased despite the overall width of the car increasing.
Generally (I could be wrong here, or anywhere...) castor kits would look to increase the castor, as it would give increased steering feel / effort but also increased negative camber on turn in and therefore more grip.