vectra cdti 150, 54 plate - vectra cdti, wheel bearing prob and brake sensor? - carnut1980

hi all, i seem to have a humming noise at 40mph plus, i have spun and shook all the wheels and there seems to be a few mm of play on the n/s/f. Should i assume there is a problem with the bearing on this wheel? all spin quietly, but theres very slight play on the o/s/f and even more on the n/s/f. Do the bearings on these come as part of the hub or seperate? Also i have a yellow light on the dash., a circle with 3 lines either side of this. All pads have plenty left on them, could this be a sensor problem?

many thanks

jeremy