mick, From reading your post it would seem that the wall you want to remove has no roof props (struts) which take the roof load.
The roof loads are not supported by all walls and are point loads down to the floor
If this is the case then the wall is not load bearing but it may be giving lateral strength. Check to see if there are any diagonal braces in the wall.
They will most likely be metal straps and you can see the ends on top of the wall in the roof space. If this is the case you will need to consult a engineer.
ps I am assuming the walls are timber.
Don't force it, use a bigger hammer.
Timber is what you use. Wood is what you burn.