In an IVA you actually owe the full debt, plus fees and statutory interest ---- over a 5 year term, on the debt of £30k, this would be around £48k, so there would be no surplus. Check paperwork though, as sometimes interest is excluded, which would bring it down to around £36k.
If there were any surplus it would be refunded to you.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014