my course is still ongoing so no reflection yet... however when we started i think we were quoted that 80% of those starting would make it out to unit (but not necessarily pass validation..), and of those 40% would do so without 'touching the sides' as it were, ie. without having to retake a failed course. check you terms and conditions to see how you stand on recourses should heaven forbid something go wrong, the rules change often. i reckon 5miles' figures for valid NATS controllers still sounds reasonable.
i'm afraid dedication is certainly required, without it you'll struggle no matter how much aviation experience you have, but no guarantees.
all i can say is, expect to work hard and you'll be ok! you got accepted so you're capable...
good luck. h10.
