It sounds as if you may have been "sold" an IVA when it was not the most appropriate solution for you (& quite possibly all the money you have paid so far has gone to the supervisor's firm & not to the creditors).
In principle there is nothing to stop someone who is self-employed going bankrupt. However, if the debts are joint (i.e. in both your name & your husband's) both of you would have to go bankrupt, as it is an individual process. There is a fee involved - normally �495.
There may be bank account problems, as bankrupts cannot get a full bank account and there are only a very few banks who will give them a basic account - & these are normally for personal use & not business accounts.
You could talk to Business Debtline (see website) about this & any other business related issues, one of which is that your self-employed husband would not be able to get any credit more than �500 (e.g. from any suppliers he buys goods from for his business) without telling them he is bankrupt.
The actual bankruptcy lasts 1 year, but if you have to make payments to the creditors (this depends on income & expenditure & is generally assessed more generously than in an IVA) then the liability to do so lasts 3 years.
Go to the Insolvency Service website & download their booklets on the implications.
If you need to, get advice from a free service (do not go to any fee paying one) such as your local CAB or CCCS.
If you do decide on bankruptcy, then don't pay over the tax rebate to the IVA, & stop your monthly payments to them. Hopefully, you would then have the money for the bankruptcy fee.