As you know, you keep 6 months salary. From that you live, as you do now, and you make the regular IVA payments, as you do now. If, at the end of the 6 months you are still without employment you can ask for a payment break, which will be added back on at the end of the agreed term. This could be for up to 6 months, depending on your IP agreeing. After that you will need to maximise income through benefits and review the IVA from scratch --- creditors might agree to a reduced payment, if it is viable. Otherwise the IVA would fail and you would be back to square one.
If you have no assets and a low disposable income a DRO might work at that point, or maybe a DMP ( which could, however, take decades !)
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014