You may want to visit
www.iva.com were you can read reviews of alot of insolvency firms.
What i have found from this forum are you often get a more personal service from the smaller firms.
I think there are a few issues that need to be considered with your case.
1. You currently have enough equity in your property to cover your debts and by allowing the charge to be placed on your property, your creditors could argue the fact you have given away equity knowing you are potentially insolvent.
2. If the charge does go through and the work carried out, as you said, what happens if it doesnt work out - you could be forced to sell your house to repay the council.
3. Assume you have the improvments to your property and it increases the value by a further £20k this would mean you have a property worth £220,000, a mortgage of £155,000 and a charge of £35k, so you would still have £30k equity so technically you are not insolvent as you have assets that outweigh your debts.
It is a difficult one, and i am sure Clearstart know the facts of your case, but i would consider taking further advice.
I would be interested to hear Ian or Melanie's adivce on this scenario.