Hi chimp and welcome to the forum
Dealing with your points in turn, if one partner is insolvent and the other is not - but all or the majority of the debts are in the insolvent partner's name, then creditors do take the view that the non-insolvent partner must have benefitted from the borrowings and is therefore responsible for paying something towards them. If these circumstances are similar to your case, then I expect your partner's surplus income to be required by creditors.
If you feel that is unfair, and have no assets which might be at risk under bankruptcy proceedings, it might be worth considering whether this is a better option for you, or putting the IVA forward with the proviso that your partner does not intend to offer her disposable income and if they do not accept then you will definately declare yourself bankrupt.
This may seem like putting bullet at the head of creditors, but I would be prepared to put a case forward on that basis.
Travel abroad whilst subject to bankrutpcy proceedings is not a problem.
Regards, Melanie Giles, Insolvency Practitioner