The R56 and R53 uses the same suspension(not exactly, but very close)
Lowering springs on a MINI with un-shortened dampers will cause many problems.
Read this post for more info:
http://minifanatics.co.za/showthread.php?pid=928373#pid928373
The spring/shock combo solution would be Bilstein B8 (same as B6 just shorter) with whatever springs you prefer, then have the shocks valved accordingly. But B8 are not available locally afaik.
Nothing less is worth it unfortunately. After the above, you can get coilovers, anything from R12k for BC to R100k for MOTON.
The most maintenance free coilover is KW, and their V1 should cost about R24k, v2 for R29k, it handles much better than stock AND its more comfortable.
Doing suspension properly is not cheap, and slapping some lowering springs on a MINI will wear out your shocks quickly and most likely wear the bushes prematurely. So unless you want to replace shocks and bushes with every set of tyres, then steer clear.