It is all laid out in the proposal --- in a nutshell, assuming the usual clauses, they will allow you to retain the equivalent of 6 months salary from any redundancy compensation, from which to make the usual IVA repayments as well as live while you are looking for new employment. Any amount over the 6 months gets paid to the IVA.
If you fail to find employment your IP might agree a payment break while you keep looking -- this break will be added back on at the end of the IVA term.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014