Hello Wiosal,
Obviously I'm not a wife so not really qualified to comment from that angle. I read your post a few times to understand it best I can.
The HT will reduce his libido. That will reduce his desire for sex, but some men will still retain some, while others won't. It will also reduce his ability to get erections and to reach orgasm, but not to zero for all men - about 20% of guys on HT can still get erections, and things like Sildenafil/Viagra, Tadalafil/Cialis, porn, etc can help, but the chances of having successful intercourse are much lower than that (some research suggests 5%, but I'm surprised it's that high).
It's impossible for me to predict how he might react to these changes, and what the extent of the changes will be in his case. It might be that his libido changes to match yours which could reduce the mismatch between you. It might be that the lack of orgasms and the resulting endorphins, possibly not even being able to go off and bang one off by himself, might wind him up more. (Many guys do this, often thinking their partners don't know, which may or may not be the case.)
There are things which might help him and you as a couple in any of these scenarios, and this is where psychosexual conselling could be really useful. Actually, given what you've said, I would have recommended this for the two of you for your current situation anyway, but the HT will change things further between you. You could both learn new things you find enjoyable to do that help you stay close, even when erections or penetrative sex might not be possible. There is usually a long waiting list for this on the NHS, so you could ask for it now, and by the time it comes up, you will have some idea how the HT might be changing things further. You could get a faster appointment if you need it and if it fits in your budget privately, which is typically around £200 per session.