The question isn't whether or not you can "co-own property as a housewife" - of course you can. The question is whether or not you can co-own property that has a first mortgage on it that you are not a participant in. And the answer to that is no.
The problem the bank has is this: As part of the deal by which the money was lent to buy the house, the bank acquired the first charge on the property. This is what gives them the right to repossess in case of non-payment.
Now, at the moment your husband (call him H) and his brother (B) co-own the house and are also jointly and severally liable for the mortgage. Suppose it were possible for you to be added to the list of house owners, but not added to the mortgage. Then suppose H+B stop paying the mortgage. The bank would be entitled to repossess the house - but wait, you own a third of it and have no contractual relationship with the bank. What happens here?
This potential conflict is why your broker quite rightly said "he just can't add me to house ownership if I am not part of mortgage deal with bank". It's also why when one is buying a house, the mortgage provider is typically very interested indeed to learn about who will be living in the house, particularly adults, so as to be sure they are not acquiring property rights without mortgage responsibilities.
I don't know off the top of my head what you can do simply to resolve this problem. If B is (as you say) happy to relinquish his share of ownership, that's one thing - but you will also need to agree with the mortgage provider that the mortgage can be transferred to you+H, and that H's income alone is enough to meet their lending criteria. Given that H has been paying the mortgage without any contribution from B, this shouldn't be a problem, but you never know.
I would recommend talking to a solicitor (specialising in conveyancing), and then with their help talking to the bank. Expect fees to be involved, in the hundreds of pounds.