Hello,
I am an Ex - Driving Test Examiner!
No problem taking the test in your own car BUT, you must have a stick on mirror for the Examiner - cheap to buy from any motoring shop.
Don't worry about the Examiner being "nervous" !! They do 35 tests per week and 140 per month ! They are VERY experienced. Just MAKE SURE you really ARE up to test standard. Your "instructor" - depending on which driving school you have learnt with SHOULD be able to advise you :)
Any further worries, get back to me.