Take it down to Quikfit and ask them to check it out.
When they have decided which side of the coin to go for, diff or bearings and while its still up in the air, whip out a long screwdriver, put the sharp end just inboard of the brake drum and put the handle to your ear then spin the wheel (dont forget to check both sides), if it goes grumble grumble graunch etc, shake your head sadly saying OOhh, AAhh, calamity, how am I going to afford that, better let me go think about it, and beat a hasty retreat.
Now, if it was the bearings, Lighthouse here we come, and if not, WELL - thats your decision, but if you get your first quote on an ARB at least the other options wont seem quite so painfull :!: