I know Logie were looking for an Islander Captain based in Glasgow, maybe its been filled but they often have vacancies anyway.
The other operator might be Hebridean Air Services?
The BN2A/B does not need a rating, you just need a Multi-engine class rating (MEP). A couple of hours on type and a LPC and you will be let loose.
The turbine Islander does have a rating as all turbine powered aircraft irrespective of weight requires a type rating.
Good luck, its a great aeroplane, but stay away from ice...
Its great for polling around though...