Basically, you should be given either the original or at least a copy of everything on the day you take the keys. There is no reason for not doing so other than 1) The housebuilder has lost them or 2) They don't exist. The fact that you legally completed on a new home without a warranty being in place, if you have a mortgage is actually mortgage fraud. CML certificates are required before mortgage funds are released.
I would advise that you submit a
Subject Access Request to K H Developments requiring all information they hold on you and your new home.
Finally I always raise an eyebrow when the warranty is not an NHBC warranty, especially if it is a small builder.
For the benefit of others, Build-Zone, according to its website has been providing Structural Warranties (it does NOT cover snagging defects) since 2003. I am not giving it a free link here but feel free to Google its website!