Hi Carl, I've never heard of the safe contractor scheme so I cannot say whether it would be worthwhile or not.
I would say however that if it helps educate in terms of safe working practises, even if it is just one new thing that you learn, then it has to be a good thing.
I'm not a great believer in memberships of trade orgainsations (BICSc, CSSA etc) but if this is safety based, and you undergo training, are regularly assessed, sit exams etc then it sounds good to me.
Musicman