SixPeaches hi, good luck at the event.
I think in some ways you will be absorbing a lot of info early in the event, perhaps at some sort of presentation. So you may find you formulate some questions during the event. You may find the question time comes at the end so take pen and paper or device to write your questions on as you think of them.
For example they may talk about the kinds of children they are placing for adoption and you may want to ask about ages, sibling groups etc and find out what kinds of situations children come from in the area.
I expect that early on you will want to explain your situation that your dh is registered blind and doesn't work and you work part time and also you are his carer. This may impact on your application and it would be helpful for you to know fairly early on whether this would be an issue for you as a couple. One thing they may ask if whether you can afford to support a child if you are only working part time. So you may wish to go along ready to answer that question. They may also ask, if you are your husbands carer part-time how it would work out with a child in the family too.
I am sure you have thought of this but I would look into how blind or partially sighted people parent generally and go prepared to talk about that if you are asked any questions. You may or may not be asked things about this and you will want to make the best use of your evening so go prepared. I am sure the charities for blind people will have helpful literature etc. I am not saying this will be the case but there are a lot of local authorities, county councils etc and voluntary agencies, you don't need to go with the one that is closest to you, and it would be good to find out which one will be most supportive of you. I just Googled 'blind people parenting' and there is massive of information, especially in from the USA. I don;t mean to go in and bombard them, I just mean go prepared.
Good luck, I hope nothing I have said has caused offence, not meant to! 