Front discs are easy, virtually any Sunny, Almera or 100NX disc & caliper will fit (with spacers to correct offset of caliper, spacers being 3-4mm washers). Choose carefully if you intend to use performance brake pads, because not all caliper variants are covered. Also watch your wheel size, not all 14" wheels will fit over a Almera Gti disc conversion.
Rears are a bit harder. Easy route is to find a Micra with rear discs, I say easy, this is the easiest conversion, but you try finding a Micra in a breakers yard with rear discs. If you find one, get the whole axle and handbrake cables and just swop the lot! We've used Sierra calipers with Almera Gti discs, but we're having problems with the back being overbraked, and are in the process of building a bias pedal box. If you want an effective handbrake (read handbrake turns!) stick with the drums.
