I'm not aware that you would need witnessed forms.
As far as I know, your bank would normally require both permissions but if NOTHING was signed, then it seems that only one person's permission would be necessary. I'm guessing that your husband may have gone into the branch but he may have put through to the telephone in the branch. However, they would normally have to at least, send you an illustration in the post confirming fees, costs etc. This would be addressed to you both and I'm guessing they would assume that both of you had agreed to it.