My whole point is that if you decide to HE alone, and your partner doesn't want it and separates over it, you can't possibly say that you will get everything that you want. You may not get custody for a start-how can you HE if you don't have the DCs with you? Even if you manage to get to be primary carer the father will get some say. I can't see any court just dismissing him and leaving it all to the mother. They will at least have to listen to his concerns. They will go for mediation and the compromises that the couple should have made in the first place.
I know full well that the LEA can't visit unless you allow it.
If I was OP's DH that would be one of the provisos that I mentioned. The LEA inspector would have to be allowed in when they wished, they would have to see the DCs and I would be there too. If he compromises by going ahead with HE I think that it is perfectly fair that a compromise comes from the OP.
My other proviso would be that we were in it together as equal partners. I get the impression that OP just wants to do it, the way she went about it shows that she isn't including him-he is just supposed to go to work and leave her to it!
At the moment I don't get the impression they are equal partners-he is more a father figure who was persuaded into agreeing and she shouted 'whoopee' rushed off and did it with no thought of anyone else at all! The poor DS has had a whole life away from her (as she has no significant worries he must have had friends) -she just took him off with no chance to say goodbye, exchange phone numbers, take in sweets for the rest of the class, bring his old books, art work home etc. Just 'here today-gone tomorrow'. She didn't involve DH is how they were writing the letter etc.
Do they even know if they have the same aims with HE? I doubt it.
I don't see how it is helpful to have couples who manage to agree on HE to just say 'tell DH to take a hike'-if he takes a hike he could kick up the hell of a fuss and she still couldn't do it! Much better to actually communicate, work as a partnership and be prepared to give and take on both sides.