If you were
only banned from driving, your conviction became 'spent' as soon as the ban ended. However, it's far more likely that you were also fined. In which case, your conviction doesn't become spent until 5 years after the date of conviction (or 2� years if you were aged 17 or under at the date of conviction).
So, assuming that you were fined, you're currently obliged to answer 'Yes' to any questions about criminal convictions. If you lie, you risk being prosecuted for 'seeking to gain a pecuniary advantage by deception'. If you got the job, you could also be sacked (without any of the rights which normally relate to dismissal) if the conviction later came to light.
The foregoing assumes that the job you're applying for isn't exempted from the provisions of the Rehabilitation of Offenders Act. Such jobs are mainly those that involve contact with children or with vulnerable adults, as well as jobs related to national security and the administration of justice. If you apply for such jobs, you'll always have to declare your conviction as it will never be regarded as 'spent' for such applications.
If you do go 'by the book' and declare your conviction it won't automatically exclude you from employment. It will be up to the employer to decide whether it's regarded as relevant. (e.g. if you're applying for a job as a van driver, it's unlikely that you'd get the job. However, if you want to work on a supermarket checkout, it's unlikely to make any difference to the quality of your application).
http://www.lawontheweb.co.uk/rehabact.htm
Chris