You like your splitters.
As far as I know, Seat Ibiza, Renault Laguna/Megane, VW Polo splitters will fit on a Micra, but will require some work for this.
For side skirts MS do some, but they are around £300 last time I seen them. I heard Corsa ones would fit with some work, but then again so will any.
Hope this helps but try the search function as this has probs been covered before.