The properties of pnictide superconductors can be controlled exquisitely by chemical doping. We have identified some key systems in which to explore this effect which should shed light on nature of the superconducting pairing. Muon studies have been crucial to understanding the new phase diagrams as they allow a study of magnetism/superconductivity crossovers as well as extracting the superfluid stiffnesses. This work is driven by an innovative synthesis programme in Inorganic Chemistry Laboratory in Oxford and forms part of an EPSRC Facility Studentship grant.