So much advice on here that's well meant but not right...
Because people are missing the point.
OPs husband is driving, and picks up a speeding ticket.
OP then proceeds to ignore the NIP, which is their one chance to let the courts know it was their DH driving, and to legitimately require the DH to take the penalty (whatever that may be).
OP now gets further communication changing them with the offence.
It's now at this point the OP suddenly "remembers" it was their DH driving, and wants to suddenly put the penalty back onto them.
From the courts point of view the OP has basically acted like every other person who tries, or has tried, or is trying to "take the points" for someone else.
Some oversights the law can live with, after all we don't live in a perfect world. However, some "oversights" - especially ones which can affect who might receive a penalty - are not so easy to dismiss.
This is a danger when you start creating black and white offences predicated on mere facts. Peoples intentions, meanings, (and excuses) count for nothing as you no longer need to prove the intent that is usually required for a conviction.
There was a spectacularly dim poster elsewhere recently who was blathering on about being done for illegal tyres. That's another offence that doesn't need any proof of intent. Dodgy tyres ? You are done, my son.
I hope the OP gets it all sorted, but it won't be straightforward. If a court appearance is needed, then the OPs DH may be required to attend, since they are going to have to admit the original offence.
Of course, the OP could now do nothing, and let the points fall on them. But that would be indefensibly illegal, and risky since we don't know what the evidence is. It could be a beautiful snap of the DH at the wheel.