Lily
Your £21,500 ought to get creditors at least 40p in the £ (HSBC will insist on this) and pay costs. If you feel that your inheritance will amount to at least this sum, my advice is go for the IVA now on the basis of a future receipt.
So long as your creditors are aware that they may have to wait for the money, that is then their choice. I have done several IVA's like this in the past with entire success.
You may even be able to limit the amount to £21,500 on a good day, therefore leaving yourself some of your Mum's money. A good IP will word the proposal appropriately for you, and put up a good case for you retaining monies to do up your house as you have previously mentioned you would like.
I would certainly not advise you to wait until the money is in the bank. Why? Interest will continue to be added, meaning more of your inheritance money is likely to be used up, and you will continue to have creditors knocking at the door.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
View my IVA blog at:
http://melaniegiles.blogs.iva.co.uk