Shugs,
I dropped out of uni twice and still got through! Been in NATS coming up 10 years.
First time was because i spent far too much time enjoying myself out of lectures and second time because i ran out of money.
The interviewers gave me a good grilling about it but I just told them exactly how it was. Where I had messed up and how I would do things differently now etc.
Don't worry about it. Just show them that you can learn from setbacks and get on with things.
Good luck.