I'm sorry you've had bad experiences with your instructors/s but something that leaps out is you don't mention anything about improving your driving and you are nowhere near test ready.
You say you've never drove 50 before.... that a 3 lane roundabout is all new to you? Given that you've had 5/6 driving instructors, 2 of them apparently long enough that they've moved or retired, I have to ask what on earth you have been doing with all this time? This is going to sound mean, but the fact you have booked a test for next month sounds preposterous with these huge gaps in your driving.