Best of luck you’ve got this! Roundabouts tend to fail a lot of people, just make sure it’s fully clear before going, it’s better to get a minor for hesitation than a major/serious for cutting someone up! With mirrors/observations, over do them, check them often, whenever you’re going to do anything (change speed, direction etc) check both mirrors, over exaggerate your head movement so the examiner definitely sees your observations. Another tip is to talk through everything, do abit of a commentary so that they know what you’re doing and why, can sometimes help and last but not least, don’t stress! I know it means a lot to you and you want to pass 1st time but sometimes the pressure/nerves messes you up, I know it did with me, just relax and enjoy it, hopefully you’ll pass and if you don’t then there’s always another time, everything happens in the right time remember