If you plead guilty you can look forward to a fine of a week’s net income, a surcharge of 40% of that fine and costs of around £95. You will be disqualified for a minimum of 12 months. Your reading (57μg) was near to the top of the band of seriousness (which covers from 36 μg to 59 μg) so you may get a slightly longer ban, up to 16 months.
You will almost certainly be offered a “drink driver’s rehabilitation course”. If you accept the offer, pay for and complete the course, your ban will be reduced by 25%.
As above, bar a major procedural
****-up, there is little wriggle room.