On the approach to the roundabout you should do a rear observation over yer right shoulder just before you start slowing down. As you set off (if you're stationary) or approaching the start of the roundabout look right and then do a quick left lifesaver.
1. Turning left = indicate left on approach to r'about, take LH lane, quick left lifesaver as you enter the r'about and finaly do a lifesaver left just before you turn
2. Going straight on = no indication on approach, adopt a position towards the left of the RH or inside lane, look right on setting off or approaching start of r'about, as the exit approaches right shoulder check, left indicator and left lifesaver B4 you turn.
3. Turning right = right indicator on approach, glancing right when setting off or approaching start of roundabout, take a nice tight line round the inside RH lane, quick left lifesaver on entering the roundabout, go round, lifesaver left after the second exit has passed by then indicate left immediately and finally do a good left lifesaver before turning.
If you do this, you should be ok. BTW I'm not an instructor but the examiner complimented me on my observations. With observations just rememberits better to do too many than not enough both from a test point of view and your safety. Thats not a licence to ride along like you're having an acute Parkinson's attack mind so be sensible.
Other observations - mirror check as soon as you see a change of speed sign/slow down at junctions or standing traffic and shoulder checks when speeding up after speed limit signs or slowing down on the approach to them. Left lifesavers when pulling out and in round parked vehicles.
Sorry you didn't pass mate - stick at it you'll get there. Hope this is useful
Good luck fer next time
Tango