dead simple mate, you'l have to remove the caliper from the carrier. two bolts. will be quite tight. Take your pads ouf first then remove the caliper.
once they are off you'l need to undo the hub nut. will be very tight. to do this i put two wheel bolts into the hub as normal (without wheel on) and put a bar through them so it cant turn, bar hits the floor and wont move. Then back of the main hub nut with a breaker bar. Pullthe disc off, put new one on. redo hub nut. Bearings come assembled already so no pressig involved. 5mins job to change a rear disc once the caliper is off