Minimum vat reclaim amount

[Oz07]

Is there a minimum vat reclaim amount?

 

I have seen somewhere councils can verify bng self build exemption by way of proof of vat reclaim rather than Unilateral Undertaking. If using a contractor to build and they are zero rating could you literally buy just like all your driveway blocks at the end and claim for only these? I suspect you'd get a phone call but surely couldn't be refused? There must be similar occurrences where people have employed a contractor upto a certain stage then finished off themselves?