You can get the Supervisor to convene a meeting of creditors to change the terms of your IVA, but the outcome is not guaranteed, as 75% of creditors must agree to any change in the terms of the arrangement, also many creditors have a blanket policy of voting against changes to IVA terms if this happens within the first 2 years after approval.
The creditors are only likely to vote in favour of a change to the terms of the arrangement if they feel that the change of circumstances was not something brought on by yourself, losing your job is an acceptable reason, choosing to leave is less so.
Philip Beck -
www.freeivaadvice.co.uk
Licensed Insolvency Practitioner and IVA specialist