Your licence is NOT ‘clean’. !! You have to declare the drink driving conviction for 5 years for any job application and is almost certain to be a no-no for driving buses, or minibuses, for that time. For many companies they want a ‘clear driving licence’ and as the DR10 remains on your driving licence record for 11 years then yes, you would not gain employment with them for that period of time.
What is supposed to happen is that when you seek employment, you get a code generated by DVLA and give that to the firm that you want to work for. They run that code and it shows unspent convictions, so after 5 years it shows up as clear.
What actually happens is that the firm offer you a job, get tour personal details including national insurance number and then run that through the online checker. Because your national insurance number and date of birth have been inputted, the system thinks that it is you that are checking for yourself, and therefore it is treated as a request: “have I got anything recorded on MY licence” and it reports any drink drive convictions in the past 11 years. (11 years is the time it is retained for sentencing purposes for ‘2 offences in 10 years = min 3 year ban)
The firm will have asked you ‘do you have a CLEAN licence?’ And you said “no” …. But that is not true. You should have been up front about it, but done your homework to see what their stance is on a ‘spent’ drink drive conviction is on gaining employment.
So the answer to your question is that you will not be able to drive a bus for 5 years, and quite possibly for 11 years. Those times run from the date of your conviction in court.