How long does it take for a conviction which will result in a fine and community order to become spent in England for someone over 18 years of age ?
Under the Rehabilitation of Offenders Act 1974 as amended by the Legal Aid, Sentencing and Punishment of Offenders Act 2012, a conviction that results in a fine and community order becomes "spent" one year after the community order ceases to have effect. This conviction will not show up on a "basic" DBS check (the sort that the average employer is allowed to get).
However, even if the conviction is spent, it will show up on a "standard" or "enhanced" check. These are the sort of check that would be done if you're applying for an "exempt" jobs such as an accountant or teacher, or for certain legal proceedings such as adopting a child.
There's also the process of "filtering". If the conviction is your only conviction, and it's for a crime that's eligible for filtering, it will cease to show up on a "standard" or "enhanced" check 11 years after conviction.