Hi Debbie and welcome to the forum
You will generally require at least a 10% deposit if you are in an IVA, and perhaps 15% is more realistic. Take advice from a mortgage broker who specialises in adverse credit lending for more definitive advice as to what is available.
As you are in an IVA the deposit monies would have to be fortcoming from a third party, as if you have that spare cash then it should be handed over to your IVA supervisor in any case.
You will need to check with the sellers of the 70/30 scheme whether you are eligible as even though you are in an IVA you are still in debt. I am sure that your IP will be more than prepared to give you a glowing reference though if this is needed.
A good mortgage broker to use is Tony Parsons of All Mortgage Products.
http://www.allmortgageproducts.co.uk/
I have enclosed a link to their website - which includes Tony's personal e-mail address which you might like to try.
Good luck in your search.
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