If my personal cirucmstaces change and I can’t meet the IVA repayments, what is likely to happen? Is bankruptcy the only outcome?

You may be forced into bankruptcy or if you have had a good record aside from your one default, with a good explanation, you may be allowed to negotiate lower payments. Alternatively, they may spread the missed payment across the remainer of your arrangement which would mean a small increase. In short, it depends on how you have been performing in the IVA up until now.

this all things depends on your having information with them.. they might take you to court if they do not get response from your side as they required.