This (and multiple other posts like it) are inaccurate.
Previous posters have conflated
Special reasons - circumstances where although there is no statutory defence, nevertheless the court can choose to impose no (or fewer) points, such as a spiked drink for drink driving or a true emergency for no insurance.
Exceptional hardship - where you should be banned but doing so would cause exceptional hardship to a third party, going beyond mere inconvenience.
Mitigation - where you say hands up, I committed the offence, but there are some mitigating factors which should reduce the penalty slightly.
There are mitigating factors available for no insurance in the sentencing guidelines, and they include remorse and previous good character, so please ignore the multiple armchair experts telling you mitigation is unavailable.
I'm sorry to shout but so many posters have said he should say "nothing" or would "make it worse" if he did, or that it "won't help" to provide any mitigation, often because they've confused it with special reasons, or just because they think he deserves a harsher penalty.
The sentencing guidelines provide the following aggravating factors: previous relevant convictions, offence committed on bail, failure to comply with current court orders or offence committed on licence. Mitigating factors include no relevant or recent convictions, remorse, good character and / or exemplary conduct, responsibility for insurance rests on another, genuine misunderstanding, recent failure to renew or vehicle not being driven.
OP's DH seems to fall into two of those mitigating categories (no previous convictions and remorse). It would be really daft not to raise them.