All of the various 'official' versions of the rules on RAS I have seen have small inconsistencies in them due to the IFR vs IMC vs not-VMC intricacies of the UK PPL rating. However, the basic principle is simple - On a RAS you have contracted with a controller that he will vector you around the sky to avoid traffic by 1000ft/5 miles and you will do what he asks. If it is unlikely that you will be able to comply (i.e. any day there are clouds in the class G airspace and you are not IMC/IR rated) you shouldn't ask. As IO-540 said, on a clear day you shouldn't ask either as you will be vectored all over the sky! Unless you weight 100 tonnes and are sliding down the ILS into Coventry.