Ian.........wood bleach won't take out stain. As I have mentioned in previous posts - wood stain is like a tattoo - more or less permanent.
You don't mention what type of wood this furniture is - but if it is not oak - or some other light color wood - it is always going to be dark. Also, if it is just a veneer - you cannot sand it - as the veneer is not thick enough - you will go right through.
Keep in mind too - that newer furniture often has diffent types of wood (or even plastic) stained and grained so it all looks the same - trying to change this can make a mess.
If it is quality furniture - I would talk to a professional refinisher - he or she can advise you. Other than that - I would either leave it alone or paint it....