I haven’t read the full thread @Holliego so I’m sure some/all of these have been suggested. I found I was massively allergic when we got a kitten and I couldn’t bear to say to children we’ll get rid so I’ve managed it
Firstly keep the kitten out of your bedroom and if your dh works from home keep kitten out of where he works as well. He needs to not stroke the cat and if he does wash his hands straight after.
Wash the kitten weekly using Allerpet Dander Remover Allergy Solution, you can get it on Amazon, bottle lasts ages. Kitten won’t like it but it will keep their fur lovely and soft. Two person job, we have a little lukewarm water in sink, one person gently but firmly holds kitten at neck (be careful) other uses jug to wet fur, little bit shampoo rubbed all over except head then rinse off and towel dry. Need to start doing this when they are a kitten, they will never like it but they will get used to it. This is really really effective.
Vacumn thoroughly and regularly with cleaner with good filter. Ideally it shouldn’t be your dh who vacumns.
I’d also suggest Air purifier in rooms where your dh and kitten are likely to be in eg living room. I mostly use AirFree purifiers that don’t need filters. More expensive up front cost but you don’t have to keep buying filters.
I use Anti histamines occasionally and have inhalers but the above measures manage it really well. I’d have never believed it when we got the original kitten as I was in a desperate state with nose constantly running, eyes bunged up and wheezing but I can now comfortably live with two cats.