@Andy Worth et al. RE: Reduced sentence
It will be reduced from what he would have got if he had not led them to the body.
This is not the same as being reduced from what any "normal" wife murderer would have got. It is very likely he will get a tariff which is something like:
X years (the murder) + Y years (the piss taking re: the pleas of innocence)
rather than
X years (the murder) + Y years (the piss taking re: the pleas of innocence) + Z years (refusing to co-operate re: the body)
So rather than saying he is hoping to get a reduced sentence you could phrase it that he is trying to avoid extra punishment for not locating the body.