i cant speak for your make (servis) but when i used to do a hotpoint it used to take just over an hour, and that was with a bearing puller, the inner bearing is smaller than the outer one, and both had to be changed along with:
bearing seal
front plate seal
heater (seeing as we had m/c apart)
Spider (drum support) since if not this will cause new bearings to go even quicker than last set as it will be worn
you may have a vitreous enamel outer drum (take m/c lid off and have a look)
these had a "back plate" which just unbolts (each bolt had a number next to it )
these were easier, but i only ever did one for bearings, as ususally the drum has a hole in it, so they were write offs (hp dont use vitreous enamel drums anymore)
if yours has a VE drum they are easiser, but do change the seal, DONT use silicone and do the bolts up in numerical order (if they are numbered)
if no numbers do them opposite to each other (it keeps the back plate flat)
tools required
for hp anyway)
various sized screwdrivers
very big spanner to remove pulley nut (sorry dont remember size, socet set too small)
U bar (jamb into pulley to stop it moving)
bearing puller
loctite thread locker (to make sure pulley nut never comes off while spinning)
Socket set to undo spider bolts
club hammer (hit spider to get it out through bearings, After pulley removed)
cold water (to drink)