Hi,
sounds like a wheel bearing starting to go, with it jacked up and supported hold the wheel with one hand at 6 and the other at 12 o'clock and rock, if you feel play get an assistant to press the footbrake while you rock the wheel. If the play goes away it's the wheel bearing, if not it's swivel or ball joint related.
Disco 2s and p38s sometimes let water and muck in through the rear seal of the wheel bearing causing roughness and noise in the bearing without showing any play or lift. If you can't feel any roughness by slowly spinning the front wheel then remove the wheel and feel for roughness in the bearing by spinning the hub, we've even removed the brake disc and caliper to get a better indication of how rough the bearing is when turning the hub.
Yes, it comes as a full hub assembly which is expensive. Make sure you slacken the big half shaft nut before strip the brakes off as they can be very tight to undo,you'll also need a big torque wrench to torque the new nut back up(32mm socket) and slacken the four hub retaining bolts from the rear of the hub carrier, a soft faced hammer to persuade! the old hub off. It's a diy job, more awkward than hard to do.
Hope this helps mate.
cheers,
Stevie
