I have had a quote from Build Zone for the warranty and building control. It came in at £6500 (which I thought was quite steep but might be OK for a 400m2 house and 100m2 annexe). They said it saves the hassle of having two sets of inspections.
I have contacted my local authority to get a quote from them too and they passed me onto Hertfordshire Building control. I am awaiting a quote from them. When I asked about structural warranty, they said to speak to LABC for a self build warranty. I have just downloaded their application form but can't see any information on here about this process? Has anyone else used LABC to get a warranty?