Hi Jonesy and welcome to the forum. I am not an expert (just up to my ears in debt!) but I wanted to reply as you sound so stressed.
First of all, make sure you can afford the repayments. I didn't and that was my big mistake as my IVA failed after 4 payments. Make sure have accounted for everything, and try and include a £50 per month contingency plan - I know about that now thanks to Melanie Giles!
Regarding your worries about the IVA not being accepted - you are returning a very high amount to your creditors. You will be paying a total of £36000 pounds (I know IP fees have to be taken into account) - have you considered talking to your creditors about a debt management plan? I'm not sure if it would be an option for you, but I'm sure that one of the experts will be able to help you on that one.
Good luck and keep posting to let us know how you get on.
Onwards and upwards!!!
View my blog at:
http://skippy13.blogs.iva.co.uk/