What is the full form of IMO please?
It stands for In My Opinion
What could be meaningful mitigation that council will consider please?
Your cat got run over, your nan died, you've just lost your job, you've been severly ill or have been diagnosed with a terminal illness, you're a victim of domestic violence, you've recently been a victim of crime, you're recently had an accident / sustained a personal injury, your nephew was recently murdered, the list is endless.
Obviously those are hypothetical examples, you can't make something up (lying in representations is a criminal offence), so you can only put forward mitigation that is true and actually applies to you. If you don't have any mitigation then you don't have it so you'll have to do without.