1. Joe Soap can petition for bankruptcy. Doesn't need to be a business
2.Both persons do not need to apply for the bankruptcy where there are joint assets however in cases where one married partner enters bankruptcy, his share of the jointly held assets is vested in the Official Assignee (Court Appointee)
3. The minimum amount for bankruptcy in Ireland is 20,000. In UK, it may be even less.
In your case I would look for an option under the new Insolvency Act.
If you go for UK bankruptcy, you will need to go and live in the UK which would probably mean that your husband would need to give up his job