Hi OP. I was first diagnosed a couple of years ago at 41. I saw a private consultant for something else and he suggested it and autistic traits. I've also had it confirmed now on the NHS.
Like your DH my mum took me to the doctor as a child, when I was 3, because I wouldn't sleep through the night. Of course they didn't know much in those days and he said it was just because I was bright and interested in the world around me.
I did ok at school and uni but struggled with motivation and my emotions at uni/college and had to drop out and in again a few times.
I was never really able to work- not at anything significant anyone unfortunately- maybe cleaning for a few hours a week.
Anyway- a friend also got an assessment at my suggestion- her problem was procrastination in particular.
It seems fairly easy to get on the list for an assessment if you say the right things to a GP (or maybe see the right person.) At least in our area (Birmingham) but services are probably patchy. It's a long wait for an assessment and then another long wait for meds.
For me it helped that I already had a diagnosis privately.
Be sure to say the right things in the assessment. (It's late sorry lol- obviously I'm not suggesting he completely lies but you have to fit your experience to it- mention anything you think significant.) If you feel you could help make sure the right things are said, go along with him to the GP appointment and assessment.
My experience of ADHD is different to many. For me it's problems with motivation and it's easy for me to not get round to doing anything. Chores are hard and I use paper plates and plastic cutlery. 
One think the consultant said is we shouldn't drink. I can't say I've followed this advice lol. But as we get older our cognitive processes decline- people with ADHD have higher risk of dementia and alcohol doesn't help our symptoms. This is more of a 'do as I say, not as I do' though.