With regards to RAS in Class G, it is a unit policy at ScACC not to provide it, not a NATS policy. There used to be an exception for Loganair flights to Carickfinn but I don't do West Coast so I don't know if that is still applicable. The only other time you will hear the words 'Radar Advisory Service' uttered by a ScACC controller is when traffic is operating on an advisory route (Class F) and also in Class G airspace when the controller wishes to resolve a specific confliction between two aircraft under his 'control'.
This last exception is, of course, a neat little cop out by the powers that be which means that should two aircraft operating under RIS have a clanger, the controller can cop the blame.
I personally believe we should give all Class G airspace to the FISO (they could do with the work) and not provide RAS OR RIS, enabling us to concentrate on the primary tasks inside regulated airspace. Maybe those operators affected would then make enough noise to the higher management/government and we would get the reglated airspace we need to provide a proper service.