Both the Haynes and Bentley manuals say the front wheel bearings and hub assembly are replaced as a complete unit and are not available seperately.
Not done this on my MINI yet but does not sound too bad a job, see below:-
Remove wheel, driveshaft nut, remove brake caliper and disc, unbolt abs sensor, undo 4 bolts securing hub assembly to the hub carrier. Reverse to fit new replacement hub.........
(Ad in Modern Mini mag says a front wheel bearing is £100 dealer or £86 from Euro Car Parts)