Thanks for that, makes things much clearer!
Now my next Q would be that after looking at the BASIX website, there is a cost benefit summary example which basically lists out…

So getting this right, the certificate itself can be done free of charge online, however the rest is pretty much parts and labour to make it comply?

I was about to post the same question but since this thread is already here I'll add to this one.
I am in the process of building a duplex with a…