Hi sm1 and welcome to the forum
First of all did your IVA proposal provide for an equity release at any stage during the period of the IVA? If so, then you will have to have good reason to want to effect this early rather than carrying on paying your contributions and then raising the money at the end of the term.
If your property was excluded, work out the value of your outstanding contributions - approx 36 months at £457 = £16452. You can take some discount for the IP fees which will not be charged so I feel your £15,000 is in the right ballpark.
What is your house worth now and how much equity do you have. It will be fairly easy to seek a remortgage - I know of companies which will now lend 95% loan to value to persons subject to IVA proceedings.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
For further details contact me at
http://www.melaniegiles.com and view my IVA blog at:
http://melaniegiles.blogs.iva.co.uk