Diff / Half shaft problems

Hi posted few messages lately ref drive problems. Thought had half shaft problem but seems to be looking more like Diff. Only got drive in the rears in diff lock. Done both checks on wheels i.e spinning them and both spin round I thought if broken half shaft one should stick after slack taken up. Prop is not spinning. You think this is most likely the diff?? Also anyone know any good mechanics/garages in the Tunbridge wells area. Am pretty new to these vehicles and don't know if I fancy stipping/changing a diff just yet Cheers